Quick Guides

*Please note that these are guides, summaries of the procedure, and should not be used in place of the full manual. For your first use, please refer to the full manual. *

SC-100A Quick Guide

SC-200 Quick Guide

SC-300 Quick Guide

SC-55 Quick Guide 

Troubleshooting pH issues on the SC-300 or SC-200



Frequently Asked Questions

General Questions

What is the Warranty/Return Policy?

Vinmetrica’s Return Policy:

A restocking fee of 15% will be charged on all returns made within 45 days of shipment, unless items are returned for repair or warranty service. ALL returns must be sent with a valid RMA number which we will assign to your item after you contact us.

If you believe that you have defective equipment we will work with you to resolve the issue and repair or replace once a diagnosis has been completed. Please contact or call +1 760 494 0597 and select Tech Support, with any questions.

Vinmetrica’s warranties and liabilities are:

1. The materials provided in the kit, as described on pages 1 and 2 of the Kit Manual, (“Materials”) are warranted as follows: Instruments, electrodes and non-reagent accessories are warranted against defects in workmanship for 12 months from date of purchase. The reagents are warranted to perform as described in the manual up until any stated expiration date or 6 months after purchase, whichever is later. THE WARRANTIES IN THESE TERMS AND CONDITIONS ARE IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT, OR FITNESS FOR A PARTICULAR PURPOSE, SAID WARRANTIES BEING EXPRESSLY DISCLAIMED.

2. Buyer agrees that its sole and exclusive remedy against Vinmetrica shall be limited to the repair and replacement of Materials or parts of Materials, provided Vinmetrica is promptly notified in writing, prior to the expiration of the warranty period specified above, of any defect. Vinmetrica’s liability for any damages due Buyer shall be limited to the purchase price of the Materials.


How stable are the reagents?

The SO2 reagents and the pH/TA reagents are all warranted to last for 1 year, and we now give a use-by date that is 2 years from date of manufacture; in fact generally all SO2 and pH/TA reagents can be used several months beyond the use-by date. To ensure best stability, always store tightly capped and out of high temperatures and sunlight. And of course, the reagents will last much longer if not cross-contaminated with each other!

pH/TA Questions

What should I do if my pH electrode is difficult to calibrate, or is acting sluggish/erratic?

NOTE: in most cases, calibration problems can be addressed by steps 1-6 below. If your electrode is slow or showing numbers way out of range, try the meter test FIRST (steps 13-16 below). The reconditioning steps (7 – 12) should not normally be needed on an electrode that is less than 6 months old.

1. Be sure your electrode has been stored at least 24 hours in a proper electrode storage solution (Vinmetrica’s product is 3M potassium chloride in 10 mM potassium hydrogen phthalate; other similar products may be used). The entire bottom 1 inch of the electrode needs to have been submerged for at least 24 hours. If this has NOT happened, wait until it has!
2. IMPORTANT! Always stir or gently agitate the solution when using the pH electrode; letting it sit static will cause drift and inaccurate readings!
3. When calibrating your pH electrode, remember that the displayed pH may not be correct until AFTER you press ENTER, and the “Good Cal” message finishes scrolling.
4. If the instrument signals stable pH (i.e., the Cal LED is flashing) but displays “Bad Cal” after pressing ENTER, try putting it flat on the table; when the next stable pH is signaled, press the ENTER button quickly without handling the instrument. Sometimes the instrument may pick up noise from its environment, particularly if you handle it at the last second, while it’s trying to achieve a stable reading.
5. If values appear to drift, leave the electrode in the pH 4.01 reference solution for 30 minutes.
6. If you intend to read pH values in samples that are at a different temperature than ambient, it’s best to have your reference solutions at that temperature also before calibrating.
7. You can restore the pH calibration and bias (DAC setting) values to factory defaults in Test Mode (see Appendix A, Section 13 in your manual). Contact tech support if you have questions beyond this.

Reconditioning and cleaning of pH electrodes

Note: before you try the procedures that follow in steps 8-12, try the simple step of soaking the electrode in your pH 4.01 reference solution for about 1 hour, then try to calibrate. Sometimes this is all that’s needed!
Even in normal use and storage, performance of pH electrodes may show deterioration over time, which typically shows up as noisy, erratic or sluggish electrode readings, and/or difficulty calibrating. Assuming the meter itself is working (see “Meter test” below), then there are two main causes for this:
A. Clogging of the reference junction (most likely).
B. Fouling of the glass membrane (happens occasionally, or after prolonged service).
The following procedures will often provide renewed stability and pH sensitivity. If the electrode cannot be restored by one of these methods, it needs to be replaced.

Unblocking the reference junction:
The reference electrode junction is usually the problem when the electrode can’t calibrate in its expected ranges. This junction is a fine-pored frit that allows electrical contact of a reference electrode with the solution being tested. It can become clogged over time.
8. Soak electrode in hot (NOT boiling!) water, about 60 °C, for 5 – 10 mins. Allow to cool to room temperature then place in pH 4 reference solution for 5 minutes. Try to recalibrate. If this does not work, try the next step.
9. Place electrode in electrode storage solution (from Vinmetrica, or 3M KCl with optionally added 0.01M potassium acid phthalate, KHP) at 60 °C and allow electrode and solution to cool to room temperature, then place in pH 4 reference solution for 5 minutes. Try to recalibrate. If this does not work, try the next step.
10. Soak in 0.1M HCl (note: this can be made by diluting 1 mL of the SO2 Acid Solution with 20 mL DI water) or HNO3 for 1 hour. Rinse with DI water, then place in pH 4 reference solution for 5 minutes. Try to recalibrate. If this does not work, try the next step.
11. Soak in 1:10 dilution of bleach in a 0.1 – 0.05 % solution of liquid detergent in hot water with vigorous stirring for 15 mins. Rinse with DI water, then place in pH 4 reference solution for 5 minutes. Try to recalibrate.

Cleaning the pH electrode’s glass membrane:
The glass bulb is a thin membrane of a special kind of glass that actually does the job of responding to the pH of the solution. It can sometimes become dirty and poorly responsive.
12. Immerse electrode tip in 0.1M HCl (see above for how to make) for about 15 secs., rinse with distilled water, then immerse in 0.1M NaOH (you can use a little of your TA Titrant for this) for another 15 sec. Cycle the electrode through these solutions several times (rinsing with DI water in between), then rinse and check for performance in pH buffer 4.00 and 7.00.

Meter test

You want to be sure that the instrument is responding correctly. A quick test is to simply short out the electrode connector:
13. Put the instrument in pH mode.
14. Remove the electrode to expose the BNC connector at the back of the instrument. Short out the terminals on the connector, using a paper clip or similar metal piece to touch the center pin of the connector to its outer metal sheath.
15. With the input shorted out, the reading should be pH 7.00 +/- 0.5. If out of this range, the meter is probably bad. Contact us.
16. Bear in mind that this test is not 100% fool-proof (the instrument might still have trouble reading pH values different from 7.00), but generally if this test passes, it is much more likely to be an electrode problem.

pH test with cream of tartar

A quick way to check your calibration and pH accuracy is to measure the pH of a saturated solution of cream of tartar which has a pH of 3.56 at 25 degrees celsius:
a. Get pure cream of tartar (grocery store stuff is fine, provided it’s pure), or even better is reagent grade potassium hydrogen tartrate, also known as potassium acid tartrate or potassium bitartrate. Call it KHT for short.
b. Place about 1/4 teaspoon of KHT in 20 mL of distilled water. Mix well for about 30 seconds. You want to be sure the solution is saturated, i.e., everything that can dissolve, has dissolved. There should be some undissolved solid left.
c. Decant or filter the solution off the solids.
d. This solution has a standard pH of 3.56 at 25 degrees C (78 degrees F). It should be within 0.02 pH of this value at temperatures from 20 to 30 degrees Celsius. Discard after 24 hours.

How much does pH measured with the SC-200 & SC-300 vary with temperature?

There is very little variance of the pH measurement of wine if you are operating within plus or minus 27 degrees F (+/- 15°C) of room temperature, 77° F. The table below will let you know what are typical readings from the pH meter using our reference solutions or other buffers at different temperatures. If you operate the pH meter close to room temperature, 77° F (approximately 25°C) , with the wine sample and the reference solutions also close to room temperature, you should have acceptably accurate measurements with a variance +/- 0.02 pH units.

If you are operating in outdoor conditions or in a cold cellar, the chart below should let you know how much variance is to be expected regarding pH buffers and our pH 4 and 7 reference solutions as well. Since most wines fall within a pH range 3.0 to 4.0, you can roughly approximate the variance in pH to be similar to a pH 3 buffer, a pH 3.49 check solution (50 mM sodium diglycolate), and the pH 4.01 reference solution provided with the SC-200 and SC-300. Even a change in temperature of +/- 27°F from room temperature doesn’t change the pH more than +/- 0.03 pH units with the three solutions mentioned above, so unless you are operating below 50°F or above 104°F, the pH measurements accuracy due to temperature variation is very close to the error of the instrument (+/- 0.02 pH).


PH Variation with Temperature

Temperature °C Temperature °F pH
pH 3 buffer (phthalate) 0 32 2.91
5 41 2.912
10 50 2.918
15 59 2.919
20 68 2.924
25 77 2.932
30 86 2.936
35 95 2.944
40 104 2.953
45 113 2.962
50 122 2.973
55 131 2.984
60 140 2.998
pH 3.49 check solution 5 41 3.47
10 50 3.47
15 59 3.48
20 68 3.48
25 77 3.49
30 86 3.50
35 95 3.51
40 104 3.53
50 122 3.56
pH 4.01 reference solution 0 32 4.000
5 41 3.998
10 50 3.997
15 59 3.998
20 68 4.000
25 77 4.005
30 86 4.011
35 95 4.018
40 104 4.027
45 113 4.038
50 122 4.050
55 131 4.084
60 140 4.101
pH 7.00 reference solution 0 32 7.115
5 41 7.083
10 50 7.056
15 59 7.032
20 68 7.012
25 77 6.994
30 86 6.983
35 95 6.975
40 104 6.968
45 113 6.97
50 122 6.97
55 131 6.97
60 140 6.974


Help! What do I do if my pH electrode was attached to my SC-300 when in SO2 mode? Is my pH electrode broken?

No, don’t worry, your pH meter should still work. To fix it, leave your pH electrode in the pH 4 calibration solution for an hour and it should return to normal function. Enabling SO2 mode with the pH electrode attached could cause the pH electrode to wear out more quickly. Because of its design, SO2 mode cannot be accessed unless you press ‘enter’ after pressing the ‘mode’ button, this is another safeguard we installed to prevent this from becoming a problem.

SO2 Questions

I added the right amount of sulfite to my wine but the numbers are still low!

This is a common occurrence with several explanations, any or all of which may be happening:

  1. Make sure you are using fresh sulfite powder. Potassium metabisulfite degrades over time and that stuff you bought 2 years ago is probably bad now!
  2. Make sure that you stir your wine thoroughly when you add sulfite. If you pour a 10% solution of KMBS into your wine, it sinks like a battleship! A sample taken off the top will read low unless the wine is stirred.
  3. A significant portion of the sulfite you added may have ended up ‘bound’, particularly if your free SO2 was very low to begin with. This bound SO2 does not show up when you measure free SO2, and it is not protecting your wine. You will need to add more sulfite until your free SO2 comes up to the right level. Sometimes you must add 2 or even 3 times more sulfite than you first calculated.

What’s the difference between the SC-100A and the SC-100?

The SC-100A is simply a new body style using the components found in the SC-200 and SC-300. It functions exactly the same, with only the audible buzzer slightly different in its tone. The reagent kits for the SC-100 and SC-100A are the same. While we no longer sell the SC-100, we still support it, and will continue to do so.

For Acid Solution Info Click here

The Acid solution is 2M (2N) Hydrochloric Acid (HCl) (6% W/W). The solution is considered a hazardous material. For the international units or reagents, we have found an acceptable method of shipping with FedEx. This is in compliance with international shipping standards. We can now ship the acid solution internationally. The acid solution will arrive in 1 ounce bottles but will function the same. This restriction also applies to shipments destined for Alaska and Hawaii.


This information does not apply to international shipments to Canada or Mexico.


If you are interested in purchasing the large 450 mL volume bottles of the acid solution or the SC-100 & SC-300 SO2 Reagent set, please email for more information.


ALWAYS use caution when dispensing or diluting the acid solution. It is not terribly dangerous but ALWAYS use laboratory protective eyewear, gloves and preferably long sleeves, pants and closed toed shoes. If you do happen to get it on you flush with large amounts of water. If the acid solution gets into the eye, walk over to a sink and flush water in your eye for 10-15 minutes, call 911 if there is any concern and consult a poison control agency, in the US call 1-800-222-1222. For poison control in other countries check out this website. Poison Centers.


Another option for getting a large amount of the acid solution would be to order 2M HCl from Sigma Aldrich, click here. You can order a liter of 2M HCl through them, while on the website it claims it is 22.70 per liter, there is also an added $15 – 25 hazardous materials charge and then the shipping cost on top of that. So the cost is from $37.70 – $47.70 plus shipping. At Vinmetrica, each SO2 analyzer kit has 100 mL of the 2M HCl Acid reagent which is good for about 50 tests, so you can imagine that you will not run out of the liter quantity anytime soon. HCl almost never deteriorates (as long as it is not cross-contaminated and is stored and sealed properly).


How does the Vinmetrica SC-100 (or SC-300) compare to other methods?

Vinmetrica’s SC-100 (and SC-300) gives results that are right in line with aeration oxidation (AO) and segmented flow analysis:

Vinmetrica’s instruments correlate very well with other methods

Also check out Dan Pambianchi’s article “Benchmarking of SO2 Analysis Instruments and Methods” on the Home Winemaking Resources page of the Techniques in Home Winemaking website: of SO2 Analysis Instruments and Methods.pdf

My SC-100 tells me the battery has only 8.5 volts, but I just put a fresh 9V battery in. What gives?

The SC-100 has a voltage drop of about 0.5 V , so a good battery will generally read about 8.5V. In fact the SC-100 will still function when the battery is well below 8V, though we recommend replacing the battery when the battery check warns you with its red LED and buzzer.

I’m getting strange results in SO2 mode; how do I know if my instrument is working correctly?

For SO2 measurements with the SC-300 or the SC-100A, there are several quick tests you can do to make sure the instrument is not faulty.

First, if your instrument does not have the latest firmware version 1.1.2, 3.1.2, or 3.2.d, we recommend that you always start with the electrode disconnected. After powering on the instrument (and, on the SC-300, pressing ENTER to confirm SO2 mode), then connect the SO2 electrode. This avoids incorrect background settings that may make the instrument appear to be insensitive or unresponsive. To determine which firmware version you have, go into Test Mode (see Appendix A in your manual, or above in this section of the Website)

To test the functioning of the instrument:

1. Be sure the battery is good per the manual’s instructions.

2. Remove the electrode to expose the BNC connector at the back of the instrument. Turn on the instrument and select SO2 mode. Short out the terminals on the connector, using a paper clip or similar metal piece to touch the center pin of the connector to its outer metal sheath. The device should indicate “STOP” with its red LED and buzzer or beeper. If this does not happen there may be a problem with the instrument; contact us for more information.

3. Connect the electrode and put it in about 20 mL of distilled water; add about 1 ml (half a bulb squeeze) of each of the acid solution and the reactant and swirl in the usual way keeping constant motion. The instrument may or may not indicate STOP as above. If it does not, add a drop of the SO2 Titrant solution. This should make the STOP condition occur. [If it doesn’t you may have an electrode problem read in the next section below how to fix this.] Now add one drop of a concentrated sulfite solution (1-10% is fine) and verify that the STOP signal ends and the PROCEED light illuminates. If this happens, your electrode is probably OK as well.

4. Finally, you can check your SO2 reagents with the Ascorbic Acid Test.

Preconditioning of the electrode Note: as of October 2013, all SO2 electrodes are shipped pre-conditioned, so this procedure should not normally be needed. Sometimes when the SO2 electrode is first shipped it can be shipped “hot”. A hot electrode is one that is overly sensitive as indicated by high readings (and STOP conditions) when inserted into solutions that should be giving no signal, like pure water or water plus reactant and acid with a drop of 10% KMBS added. If your electrode shows this behavior, it generally can be fixed by pre-conditioning as follows:

1. First, turn the power on and press the MODE button until the instrument is in SO2 mode, then press ENTER. Attach the SO2 electrode to the SC-300 analyzer. Put 20 mL of distilled water (deionized water) in a beaker and add half a bulb squeeze of the acid solution, half a bulb squeeze of the reactant solution and let the SO2 electrode sit in this solution.

2. Then add one drop of 10% potassium metabisulfite solution (KMBS) to the beaker with the electrode in it. Swirl gently. The instrument LCD should now read 0.0 (in units of nanoamps) or close to it. If it is reading significantly higher than 20 on the screen, let the electrode sit in the solution for half an hour.

3. After half an hour rinse the electrode with distilled water. Put it in about 20 mL of distilled water. Again add half a bulb squeeze of each of the acid solution and the reactant and swirl in the usual way keeping constant motion. The instrument may or may not indicate STOP as above. If it does not, add a drop of the SO2 Titrant solution. This should make the STOP condition occur. [If it doesn’t you may have an electrode problem]

4. Now add one drop of KMBS solution (1-10% is fine), swirl and verify that the STOP signal ends and the PROCEED light illuminates. If this is the case, your electrode has been conditioned. If the electrode is still “hot” and the PROCEED light does not illuminate, let it sit in 20 mL of distilled water with a half bulb full of the acid solution for a few hours. Now repeat the test from step 3. If it works, great! If not, call us and we will try to troubleshoot or replace your electrode. Our contact information is at the bottom of the page.

MLF Questions

How does the SC-50 MLF Analyzer compare to other methods?

Here is a study we did comparing the SC-50 to other methods. We get results that agree with standard analyses using very expensive equipment!

Vinmetrica’s instruments correlate very well with other methods

What are possible interferences in the MLF assay?

Very high alcohol levels may change the response of the system somewhat. The boiling step generally reduces levels far enough to limit this problem. For very high alcohol levels, you can dilute the wine in distilled water to bring the concentration below 10% ABV.
High free SO2 levels (>30ppm) may impact the Biopressure agent. Again, boiling will help this, but if needed you can dilute the wine sample as above.

What is the effect of temperature on the MLF assay?

Temperature can have a significant effect on the assay. The recommended temperature is standard room temperature, or about 70 °F (21°C). Temperatures within 3 degrees °F (or 1.5 °C) of this value should be fine. At lower temperatures, the rate of the Biopressure reaction slows down, and the pressure change also is lower, just like car tires lose pressure in cold temperatures. Therefore the assay is less sensitive at lower temperatures.

At higher temperatures, the opposite effect occurs: the reaction will go faster and generate higher values. In principle this is not bad per se – the assay becomes slightly more sensitive with the higher pressures generated. There is nothing wrong with using a higher temperature up to about 95°F (35°C), with two cautions: 1. the higher pressure resulting from higher temperatures may throw off the instrument’s 50 nA set point so it now will signal at a level below the 0.1 g/L level – therefore you will have to pay attention to concentration calculations; 2. most users’ environments aren’t set up to control higher temperatures that well, so increased variability may result. A warm water bath with controlled temperature can be used.

Services Page FAQs

Vinmetrica Labs Quality Guarantee

We offer quality laboratory testing for brewers and winemakers. We believe our clients should be guaranteed that their samples are handled with the utmost care and to the highest standards. Our laboratory services will be performed following the rigorous AOAC and TTB approved wine and beer analysis methods.

We try to minimize our changes in price for our laboratory services as much as possible. But the laboratory service prices can vary from time to time depending on the time of the year. All reports are strictly confidential and are meant for client’s use only. Our prices on our website reflect our up to date pricing.

Note: We are not responsible for wine samples that are improperly packaged, damaged or deteriorated during their shipment. Please contact us if you have any questions or concerns regarding shipping and handling. Our contact email: and our technical support and sales phone number is (760) 494-0597.

Receiving your Shipping Supplies

We send shipping supplies to you, free of charge, once you place your order.

Please make sure to send us your samples in a tightly sealed container per the “Wine and Beer Sample Shipping Preparation” instructions. Be sure to mark each sample, marking such as “Merlot A” or “Merlot B” are sufficient as long as you know which sample is which. The more detail the better.

*If you are sending an entire bottle, please let us know in the Customer Notes section during checkout.*

The Shipping Supplies includes everything below, with the number of tubes and size of the box based on how many tests you purchase:

• Cardboard box for returning the shipment
• 50mL or 15mL conical tubes (one for each analysis or two if the analysis requires a 100 mL sample)
• Vinmetrica Labs Conical tube labels
• Gel pack and Styrofoam container (for certain sample analyses, if sample requires being kept cold)

Once you have prepared your sample from the ‘Wine & Beer Sample Shipping Preparation’ instructions, make sure to attach a shipping label to the top of the cardboard box and ship to the address below. Please write on the box “For Laboratory Analysis Only”.

If you are near North County San Diego, feel free to stop by and drop off your sample Monday through Friday 9-3pm (please drop samples earlier in the day so they can be processed in a timely fashion). Our address is:


6084 Corte Del Cedro, Suite 105

Carlsbad, CA 92011

Beverage Sample Shipping Preparation

Shipping Preparations for Beverage Samples

Note: We recommend that you do not ship samples on Friday or Saturday as the samples could be compromised over the weekend due to deterioration of the sample. If shipping Thursday, make sure to ship via overnight, so the samples do not sit over the weekend.

1. Upon receiving your Vinmetrica Labs sample shipping kit, please place the gel pack in the freezer for 12 hours or until the gel pack is frozen solid.

2. Prepare the sample by filling up either the 15 mL or 50 mL conical tube then cap and seal tightly. Look on the Vinmetrica Labs Label for a Min. Volume necessary for that specific test.
Note: Fill the conical tube to a level above the beginning of the threads near the top of the tube to reduce headspace. (this is a volume either over 15mL or 50 mL depending on the size of the tube)

3. Fill out the Vinmetrica Labs label that is provided. Check the box for the test that you wish to be performed on your sample. Please include a phone number and an email address on one of the labels. Place the label on the tube so the label is not overlapping itself.
Note: One analysis per tube. Please only check one box per conical tube. Analyses require a certain volume which will be either the 15 mL, 50 mL or 100 mL Min. Volume category. For 100 mL analyses, please fill two 50 mL conical tubes as per the instructions above.

4. Repeat steps 2 and 3 for all sample analyses ordered.

5. Place the samples in the ziploc bag provided and seal shut. Place the ziploc bagged samples and the frozen gel pack into the styrofoam box.

6. Place the prepared styrofoam box into the cardboard box that is provided. Tape and seal the box closed. Print out a shipping label addressed to us (our address is below) and please write on the label, in a conveniently readable location, “For Laboratory Analysis Only”.

Note: The shipping supplies are provided free of charge. Expect arrival in 3-4 business days for handling and delivery of the supplies.

For Local Drop-off

If you are near North County San Diego, feel free to stop by and drop off your sample Monday through Friday 9-5pm. Our address is:


6084 Corte Del Cedro, Suite 105

Carlsbad, CA 92011


Shipping Questions

Canadian Customers Click Here

We ship to Canada via FedEx Ground. Vinmetrica does not pay for any duties, taxes or fees that are applicable upon entry but all freight charges are included. Click here to return to our North American Products page.


If you would prefer, you can purchase one of our products through our Canadian distributors. Click on the link above for a list of our distributors.


International Customers Click Here

If you are outside North America we must ship the acid reagent, 2M HCl (2N HCl) found in the SC-100A & SC-300 analyzers, the Pro Kit and the SC-100 & SC-300 SO2 Reagent kit in small 1 ounce bottles because of hazardous materials restrictions imposed by international shipping standards. This does not change the function or concentration of the acid solution and you still use 2 mL of the acid solution for each Free SO2 test.


If you are purchasing the large 450 mL volume bottles of the acid solution or the SC-100 & SC-300 SO2 Reagent set (these large replacement bottles which are sold separately from the units themselves), the acid solution will arrive in small 1 ounce bottles as well.


Similarly, we must ship the 100 mL of 1M (1N) NaOH solution in 1 ounce bottles (an optional item for doing Total SO2 analysis – not included with the analyzer or reagent kits) when ordered internationally because of these hazardous material restrictions.


Another alternative shipping method is to contact one of our distributors. If one of our international distributors is close to your location, we can get you in contact with them. Feel free to email,, or call us, if you have any questions regarding international shipping. We are available Monday – Saturday, 9am – 5pm PST: +1 (760) 494-0597


For more information on the Acid reagent check out the link below.


SC-100A & the SC-100

  • Sensitivity: detects less than 2 ppm Free or Total SO2 in a 25 mL sample
  • Accuracy: +/- 2 ppm Free or Total SO2


  • pH range: 1.0 to 13.
  • Accuracy: better than 0.02 pH unit.
  • Autocalibrate on pH 3.00, 4.01, 7.00, 10.00
  • TA mode: Accuracy: +/- 0.2 g/L Tartaric acid.
  • Sensitivity: Detects down to 0.2 g/L Tartaric Acid


  • Combines the specs for the SC-100 and SC-200


  • Sensitivity: better than 0.04 g/L malic acid (3 mL sample)

Data Sheet

SDS Sheets

SO2 Titrant
Acid Solution

pH7.00 Reference
pH4.01 Reference
TA Titrant


Boost Juice
Malic Acid

Reaction Buffer
Buffer Solution

YAN Neutralizer

ABV Developer
Calcium Hydroxide Neutralizer
ABV Oxidant
ABV Starch Indicator
ABV Titrant

Do you have a question that we haven’t answered here?
Not a problem, type it in below!

168 thoughts on “Support

  1. I haven’t used my Vinmetrica SC-300 for a few years and the storage solution in the pH electrode has dried up. Is the electrode still good? If so, what should I put in the bottle?

    1. Gene,
      You can try soaking it in fresh pH electrode storage solution for a day or two to try and bring it back to life. If you don’t have any then I would temporarily soak it in the pH 4.01 reference solution while you order and wait for some fresh solution. This has worked on electrodes in the past. The pH electrodes typically last about 2-3 years so if yours is significantly older than that it might just be best to get a new probe. Totally up to you. Let us know if you have any more questions.

  2. Is there information available which shows the performance differences in different firmware versions?

    What is the firmware performance difference between SC-300 with firmware version 3.1.2 & firmware version 3.2.d?

    There certainly is a difference in the SO2 probe connector! I also have 2 SC-200’s with different firmware. I know firmware version 2.0.2 will not show “Potential Mode”.

    SC-200 firmware 2.0.2 – Potential Mode not present
    SC-200 firmware 2.2.d – ????
    SC-300 firmware 3.1.2 – ????
    SC-300 firmware 3.2.d – ????

    Reading the SC-200 manual, I see firmware 3.1.2 was installed in the SC-200 at some point of production.
    Is this the same firmware 3.1.2 which is in my SC-300?


    Does each product have its own unique firmware numbering plan?

    1. Roger,
      Thank you for contacting us. All the firmware versions should function almost exactly the same while in regular analysis mode. The main difference between some of the older firmware versions and the newest one is the addition of the potential or mV (milli-volt) mode. On the SC-200 and SC-300s, this mode is indicated by a blinking pH LED. It comes after the pH mode and before the TA mode. You can cycle through using the MODE button to find it.

      SC-300s with the 3.1.2 firmware essentially have all the same functionality as SC-300s with the 3.2.d firmware. The only difference is that the 3.2.d firmware is for the newest version of the circuit board. The 3.1.2 version is the original version of the circuit board. I believe the circuit board change took place about 4 years ago.

      With the changes to the circuit board and the updates there were also some updates to the overall design in order to make testing easier for our customers. This included a change to the connector on the SO2 electrodes and subsequently the connector on the units for the SO2 electrode.

      SC-200s with 2.0.2 will not have potential mode but 2.2.d would have it. If you cycle through the modes on the instrument, this will be indicated by a blinking pH LED. This should happen after pH mode and before TA mode which hitting the MODE button to cycle through.

      That might be a typo in the manual. The SC-200s get the SC-200 firmware and the SC-300s get the SC-300 firmware. The main difference between the SC-200 firmware and the SC-300 firmware is that the SC-300 firmware has the code written on the circuit board for testing SO2, as the SC-300 is designed to test for SO2, pH and TA whereas the SC-200 is only designed to test for pH and TA.

      I hope this answered all of your questions. Let us know if we can help in any other way.

      Thank you

  3. Hi – I have the SC-300 (software 3.2.1) and I’m having trouble with the pH probe calibration. Values are coming in outside of the 0.5 pH dead band, and I’m trying to see if force calibration results in a good Cal (it’s been a couple years since I used the probe). I followed the instructions to get to the dead band setting (option 14) but my option 14 is SO2 baseline. As best as I can tell, all the other options are doing what they are supposed to, except this one. Am I missing something? Next step is to clean and refill the probe, but I’d rather skip that if possible – I noticed the pH 4 and 7 measured values (fresh solutions) are offset by a constant amount, so I’m not feeling like replacing the probe just yet. Any way to update the software? Thanks!

    1. Pip,
      Thank you for contacting us and thank you for trying to utilize the test mode features.

      It sounds like you may be operating off of the old guide for the test mode features but we should be able to get this resolved. Go back in to test mode and cycle through until you hear the loud beep (indicating the testing of the sound feature). Press the power button twice and the screen should scroll and say “Press Enter”. Go ahead and press enter and it should say Good Cal across the screen. Hold down the power button to exit out of test mode. That feature helps reset your pH settings back to their original factory settings. This wil help us diagnose what might be happening with your unit.

      Now try and calibrate your pH electrode. In 4.01, what does it read? In 7.00, what does it read? If it is showing up outside of the +/- 0.5 pH units then the unit will not calibrate. Since you have the newest version of the firmware, navigate to mV mode (this is the mode right after pH mode where the pH LED is blinking) Make sure your pH electrode is attached and put the probe in the 4.01 and the 7.00 solutions. What is the unit reading? Our rule of thumb is that, when in pH 7.0 reference solution, and with the unit in mV mode, the value on the screen needs to be 0 +/- 15 units. If your electrode is reading out of this range then the problem is most likely with your electrode and it should be replaced. The pH electrodes typically only last 2-3 years. If it is within this range then your electrode should calibrate okay. Sometimes if the electrode is older, it may need to be calibrated a few times to make sure that it holds its calibration. There is a white tag on the cord of the electrode with a month and year listed. What does it say? If its still not working, a phone call to our tech support line might be the best thing to do.

      It is always good, especially if the electrode hasn’t been used in a while, it would be good to clean the probe and replenish the solution that it is in. To clean the probe, soak it in 1N NaOH if you have some or even your TA Titrant, if not you can soak it in your SO2 Acid solution, for about 30 minutes. Make sure to do this in a separate container as particulates might comes off and you don’t want that in your solution bottles. You should also make sure that the solution in the pH electrode storage solution vial is clear and fresh.

      You mentioned an offset value? What are those values? Your software is the most up to date for your unit. About 4 years ago, we released a whole new version of the circuit board with an updated firmware but your firmware version is pretty similar to the firmware of the new version of the device.

      Let us know what other questions you have, or you can always call the tech support line for further assistance.

      Thank you

  4. I’m new to the testing process. When I am doing the SO2 test I start out with the reading below 50. When I add the titrant the meter eventually starts beeping and goes to 1999. I stop adding the titrant but it stays at 1999. Am I doing something wrong? Should I keep adding titrant? I read the meter should go above 50. I do have the electrode for the pH on the meter but I set the meter to the SO2 test.

    1. Bill,
      Thank you for your questions. The basic testing procedure is as follows:
      Testing for SO2: (assuming your meter is is newest model available, purchased within the last 3 years)
      1. Navigate to SO2 mode and attach your SO2 electrode. The meter should read 0.00, or at least under 50
      2. get your wine sample (25mL) and remember to sterilize your pipette before removing the sample from your barrel or carboy. We use Kirkland Vodka as our sterilant. Spray and wipe down the pipette then grab your sample. Place sample in 100mL beaker(provided).
      3. Add approx 2mL of the Acid Solution and 2mL of the Reactant solution to the beaker with your wine sample. Mix well
      4. Place your SO2 electrode in the solution.
      5. Fill your 5mL syringe or glass burette with SO2 Titrant and write down your starting volume, indicated on the side of the syringe. We usually fill ours all the way up to the 0.00 mark so it makes for some easy math at the end.
      6. Make sure your sample is mixing at all times during the test. Now, using your 5mL syringe or a glass burette, if you have one, very slowly add in your SO2 titrant, drop by drop until you are able to count 20 consecutive beeps on the instrument. Make sure the solution is stirring at all times until you have reached 20 consecutive beeps. This indicates that you have reached the endpoint of the titration and your test is done.
      7. Note your final volume on the syringe.
      8. Now take your final volume minus your initial volume (this is the amount of titrant you used for the test) and then multiply that value times 20. That will give you the ppm of SO2 in your wine sample.

      If you are in SO2 mode and your SO2 electrode is attached, and you are using your SO2 electrode for the testing then you should be okay. You can keep the pH electrode attached to your unit while testing. Some people keep both attached so that they do not lose one or the other.

      If you find that you are adding only one drop of SO2 titrant to the beaker before the instrument sounds off and goes to 1999, if may mean that you have no SO2 in your wine.

      There are videos available on our website that should help with a visual of what the test looks like.

      Let us know if you have any additional questions.

  5. Can I use distilled water rather than DI for TA test

    1. Warren,
      Distilled or DI water are okay to use. Make sure they are fresh too.
      Let us know if you have any questions.

  6. Hi,

    We specialize in fruit wines at our winery and I’ve noticed that my free SO2 reading with my peach wine is always >100ppm, which I find nearly impossible. Testing works fine on all of the other fruit wine varieties that we make, except for peach. I talked to someone that thought maybe it was the high vitamin C content of peaches giving a false positive.

    We use the SC-300 model. Any help would be greatly appreciated. Thank you.

    1. Jake, it is indeed possible that peach wine contains sufficient vitamin C to interfere. In that case you should run free SO2 by a different method. Aeration Oxidation is a good choice. We can run that test here in our Service lab if you like.
      Best regards,

      1. Thanks for the timely response, Rich. I will keep that in mind and be in contact if needed.


  7. I need to send in a sample of “grain on” whiskey mash to be tested for YAN. Is that test possible with a thin-ish flour mash?

  8. My so2 probe isn’t reading anything on my sc-300. In finished wine or fresh wine that i just put s02 in, it just always 0.0.
    The connection is tight an seems fine. Is there any solutions to this, or do i most likely just need a new probe?

    1. Matt, to test the SO2 function, follow this test:
      Connect the electrode in SO2 mode and put it in about 20 mL of distilled water; add about 1 ml (half a bulb squeeze) of each of the acid solution and the reactant and swirl in the usual way keeping constant motion. The instrument may or may not indicate STOP as above. If it does not, add a drop of the SO2 Titrant solution. This should make the STOP condition occur. [If it doesn’t you may have an electrode problem read in the next section below how to fix this.] Now add one drop of a concentrated sulfite solution (1-10% is fine) and verify that the STOP signal ends and the PROCEED light illuminates. If this happens, your electrode is probably OK as well.

    2. I am having a similar issue. I have a new probe, but the connection seems off. I often do not get a reading, but I if hold in metal connection from the probe to the SC-300 unit, I will start to get readings. But, I shouldn’t have to hold onto the probe connection for it to work. Any info is greatly appreciated.

      1. Jennifer,
        Did you try the test that was mentioned? Connect the electrode in SO2 mode and put it in about 20 mL of distilled water; add about 1 ml (half a bulb squeeze) of each of the acid solution and the reactant and swirl in the usual way keeping constant motion. The instrument may or may not indicate STOP as above. If it does not, add a drop of the SO2 Titrant solution. This should make the STOP condition occur. Is this what you were doing when you started holding on to the probe connection?

        If your instrument has an RCA (phono-style) connector for the SO2 probe, it may need physical adjustment to ensure good contact of both conductors (we can help explain how to do this over the phone). The older and newer versions have BNC (twist-lock) connectors don’t usually have this problem. Sometimes corrosion can occur at the connection and the connector may need to be cleaned off. You can contact our Tech Support line for further information and we can help you walk through these tests too. 760-494-0597 and select Tech Support.

  9. Hello, we purchased an SC-200 back in October from Presque Isle Wine when we went and picked up our fall juices. I must say it is one of the easiest and stable devices I have used in a long time. While we use it for ph and TA, we realize it would be better if we had bought the SC-300 as it has much more versatility and tests available like Free SO2 and YAN.
    Do you offer any kind of trade in policy on our SC-200? It is almost new and has only been used a few times. We would like to upgrade.

    Thank you,
    Kevin Croak
    Harmony Winery, Fishers Indiana

  10. Hi! My local store is suggesting I use a TA Titrant of 0,1 N or 0,2N (sodium hydroxide) as a replacement of the TA Titrant that came with my Vinmetrica SC-300 kit.
    Will I get the same results?

    1. Marcel,
      Thank you for contacting us. The 0.133N NaOH (TA Titrant) that we make is specifically designed to be used with our kit when testing your TA levels. You can use the 0.1N NaOH as a replacement for the TA Titrant however there will need to be adjustments made to your final calculations. You cannot use the simple equation listed at the end of the procedure (TA = 2 * V). You will need to use the longer equation listed above it and replace the 0.133N with the concentration of the NaOH solution that you use. This may blur your endpoint slightly so do take care when performing the titration and make sure to not overshoot the endpoint.
      Let us know if you have any questions.

  11. Good Morning,
    I have a question on the MLF 55 unit. How can I tell that my wine sample has boiled for 60 seconds. Should it bubble for 60 seconds? I’ve tried using the microwave on low and the wine never bubbles, but will kind of sputter violently once or twice. When it’s done it usually has 5ml left. I tried boiling water on the stove and using it as a water bath but the wine sample never seemed to boil, and when I finally pulled it out it was 3ml. I put a thermometer in the wine and when it hit 175F i timed 60 seconds and then pulled it out. I don’t trust the results of the MLF test because of this issue. As silly as this sounds it would be very helpful if you could post a video showing how to boil the wine or a bit more specific instructions on boiling the wine.

    If I pull all the chemicals out of the freezer can I reuse them again, i.e. can I pull them out of the freezer, let them come to room temperature, use what i need and then re-freeze them?


  12. A couple questions regarding pH/TA testing with your SC-200.
    1. I get a “Good CAL” with 4.0 & 7.0 buffers and get stable readings on wine samples. However, I can never get a stable pH reading on distilled water. Is it possible to test the pH of distilled water?
    2. When testing TA, I typically get a lower pH reading after adding 15 ml distilled water to the 5 ml wine sample (i.e. wine is 3.49 pH and wine with 15 ml water is 3.42). This looks like my distilled water may be slightly acidic (hence question #1 above). Does this skew my final TA results?
    FYI – I’m using super market distilled water which I boil prior to use and always top with argon gas.

    1. 1. It is possible to measure the pH of distilled water, but it’s tricky. In principle pure water has a pH of 7.00 at normal temperatures, but as atmospheric CO2 dissolves in the water the pH will drop slightly due to the formation of carbonic acid. In addition, most distilled water from the store, (which by the way is usually de-ionized, rather than distilled), may have very minor amounts of acidity or alkalinity that takes the pH away from 7.00. So even if you degas and boil, as you have, you may find the pH still not hitting 7.00 and in any case it will start changing immediately on exposure to air.
      However, the pH of your distilled water is unimportant for almost anything you want to do with it, because the water has negligible buffering ability. If you were to take 25 mL of it and do a TA titration for example, you will see that less than 1 drop of TA Titrant takes it to way above pH 9, so in essence it has no detectable acidity.

      2. The reason that the pH of wine drops on adding distilled water has nothing to do with the water or, up to a point, with the degree of dilution. Rather it has to do with the nature of the pH electrode and how it measures pH. pH is generally considered to be -log[H+], i.e., the negative logarithm, base 10, of the hydrogen ion concentration, but formally it is defined as -log(hydrogen ion activity). Activity a and concentration c are related but not identical: a = g x c where g is the “activity coefficient”. It is this coefficient that is changing as you dilute your wine, becoming closer to 1 with dilution. The pH electrode responds to hydrogen ion activity, rather than its concentration per se.
      Also, since wine is a fairly strongly buffered system (primarily by the tartaric acid/tartrate ions, and other acids present) you would have to dilute it over a thousand fold to change the hydrogen ion concentration.

      NB a.) to check your pH calibration, suspend about 1/8 tsp (0.5 g) of pure cream of tartar (aka potassium hydrogen tartrate) in 20 mL of water, stir to dissolve for 30 sec. Some crystals will remain. This saturated solution of cream of tartar has a standard pH at 25C of 3.56. I am good with 3.50 to 3.60. If not, try recalibrating. Make this fresh each day.
      b.) Be sure to always stir or swirl your solution when calibrating or measuring, i.e. do not let the electrode sit stagnant in the solution. You will get considerable errors in your pH measurements.
      Hope this is helpful.

      1. Richard,
        Thank you so much for the quick response and incredible detail. And, yes, your explanation is very helpful. GB

  13. When the YAN test is completed and the neutralizer is added does this make the YAN test safe to dump down the drain or do we still have to dispose of it in a special manner?

    1. Brian, the small amount of formaldehyde in a test is neutralized entirely by following the procedure in the manual, and since the pH of the solution should be less than 9 at that point, there should be no problem in sewering the test’s contents. However we can’t anticipate all local regulations, so you may want to check.

  14. The SC-300 kit comes w/ 2 burettes but not the stopcock. How do you use them w/o the stopcocks?

    1. Dan, the SC-300 kit comes with a 25 mL and 5 mL pipette but not a burette. These pipettes are for taking samples for SO2 and TA testing, respectively. For titration you use the syringes in the kit.
      We do supply a burette in the SC-300 Pro Kit, or you can get one in the Deluxe kit that comprises the extra items in the Pro Kit. You can also order just a burette if you like.
      All best,

  15. Is the SC-300 temperature compensated? I’ve calibrated the unit w/ both the 4.01 and 7.0 solutions. Get different readings between inside the house and the 52 degree tank.

    1. Dan, the SC-300 does not have temperature compensation (ATC), however the difference in a pH measurement between 52F and 70F for most solutions is pretty small, less than 0.05 pH units in most cases depending on what the solution is.
      If you need to make measurements at 52F, for best accuracy we recommend calibrating with 4 and 7 solutions that are at that temperature. You can check calibration at room temperature with a saturated solution of cream of tartar (potassium hydrogen tartrate, KHT for short). Add 1/8 tsp KHT to 20 mL distilled water, stir for 30 sec. pH is 3.55 at 70F. At lower temperatures the saturated KHT is not standardized, but will be between 3.50 and 3.60, so you can confidently check your calibration at 4 and 7 this way.

  16. I own a SC-100 and want to make sure I purchase the correct replacement electrode. For the replacement SO2 electrode shown in the picture, I want confirm that it’s a Female BNC Terminated one that’s shown.

    1. Bruce, check out this link Electrode_Guide to guide you in selecting the correct SO2 electrode. Thanks!

  17. With the SC300 kit how many tests can be performed with the reagents that come with it??

    1. Eugene, the SC-300 comes with sufficient reagents to perform about 50 SO2 tests and about 30 TA tests. The reagents have a 2-year shelf life.

  18. Hi

    Hope all is well. I have a small vineyard and was wondering if you knew of a company or person who could take the grapes and make wine. Looking fw to your reply. Thanks in advance!

    1. Tom, I don’t know for sure. Where are you located? If in Southern California, as we are, I might be able to pass your query on to some local sites.

  19. Recently I used the SC-300 Kit to analyze a few of my home made wines. The kit and electrodes worked fine and I was able to get Ph, SO2, and TA values that made sense. The Ph calibration, testing, and subsequent titrations via the two electrodes went well.

    I then tried to test the six wines for ABV. I thought I was on the right path when I titrated the blank and got a 9.0ml result, which was consistent with the value cited in Table 1 of your user manual. However, when I did the titrations on the sample, the color, after incubation, was a clear medium blue and I did not get the color changes expected with the blank and noted in the manual. Eventually, after titrating volumes that were well beyond what was expected, a white-gray precipitate formed.

    I purchased the ABV kit March 2017, and it was stored in my wine making room. I did not open the reagents until I used them.

    I was very careful following the instructions about keeping the sample in the bucket and not letting the oxidant splash into the sample.

    Are the reagents too old, which does not make a lot of sense, since the blank was consistent with the user manual? Did I do something that created the problem?

    1. Richard,
      this result indicates that too much alcohol was put into the bucket. If you are pretty sure that your wines have less than 20% ABV, then check to make sure you are adding exactly 100 microliters of sample. Two mistakes commonly seen are: 1. the pipettor is not set to deliver 100 microliters. The setting is seen at the top of the device and can be as high as 250 microliters; 2. Be sure to follow the pipetting instructions carefully. It is important to expel the liquid using the first “stop” in the plunger’s stroke.See Appendix A in the manual. Contact us if you need more help. -Rich

  20. Sorry to bother again Richard.. ha ha! Just thanking you for your great help today – you’ve answered many questions I’ve been asking myself for some time. I in fact DO use sorbate at this time to stabilize the wine, however I am still told to keep the wine very high in the sulfite levels so I make sure to do so diligently. I agree with your idea that with sorbate I do not necessarily need that much SO2 in the wine but if it cannot be sensed by myself or others, why not? But less is better in so many things so I would rather not go overboard. At any rate, I appreciate your answers, and I have personally ordered the 1N NaOH 450mL solution from your store, regardless of what my father wishes to do at this time!
    Thanks again,
    Josh @ Tongue River Winery

  21. Dr. Sportsman, regarding the total SO2 test, I have a couple questions.. I did not realize the test called for 1N NaOH instead of .1N NaOH and so when I performed the total titration I incorrectly used .1N NaOH instead of 1N. I was given an end result of about 28-30 ppm total SO2 in the wine. I am curious as to whether or not this could just be considered to be 280-300ppm total SO2 since the NaOH is merely 10% as strong as it would have been as a 1N sample? Would I have to use 15mL of titrant to calculate 300ppm of total so2 using 1N NaOH? Also I wonder if it is possible for the total amount of SO2 to decrease over time such as does the free SO2 level? Depending on the wine, the government rule of 350ppm total SO2 is hard to stay under sometimes if I want to keep the molecular level of SO2 high enough to feel safe about wine stability, but I also don’t want to go too high because of taste, color change, etc. etc. Thanks for any help!

    1. Josh, There is no factor to correct for using 0.1 vs. 1 N NaOH; you simply did not achieve the necessary high pH to cause release of bound SO2. Your result of 28-30ppm probably reflects mostly free SO2.
      Yes, you would have had to use 15 mL of SO2 Titrant for a total SO2 level of 300 ppm.
      Total SO2 will decrease with time generally because it can still undergo oxidation to sulfate under the right conditions. So you might be under TTB maximum levels of 350ppm total sulfite (SO2), but if resulting sulfate levels rise above 200 ppm it can be picked up as a bitter taste.

      1. Thanks Richard! Quick reply, almost all I needed to know 🙂 It seems like a tough test to perform with just the 5mL syringes if I have to use 4 of them just to see if I have 200ppm of total SO2 in the wines. Most of these that I make end up with over 200 total every time because of adding a ‘crucial’ dose just before bottling a sweet wine and getting over 1.25 molecular. Is this too high? I have been told time and time that with a sweet wine I need to keep this level so high to make the wine stable enough to be comfortable with it professionally. I sure do not taste anything above 200ppm but I am just the maker. Sorry to bother, thanks for the help.

        1. Sorry Richard I got carried away.. above I meant 2 syringes – what I really forgot to ask is could I just use 10 times the amount of .1N NaOH in the test to replicate the 1N NaOH (i.e. 100mL .1N instead of 10mL 1N)? My father doesn’t want to buy any 1N NaOH if possible!


          1. Josh, In principle you could do this, but normally it will dilute your whole test quite a bit making the endpoint difficult to see. However, if you know your Total SO2 is going to be above 200 ppm you might get away with this: take a 5.0 mL sample instead of a 25 mL sample. Add 20 mL of 0.1N NaOH, then after the 10 min incubation, add 3 mL of the Acid Solution rather than the 8 mL specified in the manual. Proceed from there.
            Finally: why don’t you use potassium sorbate to stabilize the wine? works better than high SO2.

  22. Good Afternoon,

    I have a question on the SC-55 MLF analyzer. Can you please tell me on average how much of the wine sample is left after putting it in the microwave for 90 seconds. I wanted to get an estimation of the amount of wine left so i can see if I am properly heating the wine.


    1. Joe, typically 7 to 8 ml of wine should remain after the microwave heating. Be sure and let it cool completely after making it back up to 10 mL! Thanks.

      1. Rich,

        Thank you for your quick reply. I had a sample that was reduced to 5ml after the microwave and it showed the wine as having completed MLF. Should I re-check the wine making sure its in the 7-8 ml range after microwaving?



        1. Joe, I would guess you’re OK with the results you got. Thanks,

  23. I have a SC-300 analyzer and I’m unable to conduct the SO2 test. A couple observations:
    1. My connector tip on the analyzer spins freely, it is not a fixed connection like the TA/pH connection…is that normal?
    2. I did not receive the Acid Reactant the instructions say to use. But the manual is contradictory because in one illustration is states I can use either the acid OR the SO2 reactant…which is it?
    3. My analyzer is blinking 0.0 while it sits idle in ‘proceed’ mode…is that normal.
    4. Most important, I’m not getting any kind of reading on the analyzer…is it because I did not add the acid reactant?

    I’m very concerned at this point I have a bad analyzer!

    Please email me a way forward…


    1. Scott,
      1. the connector tip may spin freely if it is an older RCA (phono) plug type.
      2. For SO2 tests you should have 3 solutions: SO2 Titrant, Acid Solution, and Reactant. You need to add about 2 mL each of Acid solution and Reactant to your sample, then titrate dropwise with the SO2 Titrant.
      3. It is normal to see 0.0 on the display at the beginning of a test but:
      4. If the display never goes above 0.0 during the titration there may be a problem.
      If indeed you have the older RCA plug, it sometimes fails to make good contact with the receptacle at the outer grounding ring; in that case try squeezing the outer grounding ring on the plug by ever so slightly compressing it with a pair of pliers.
      To test the function you can use this from the Support page of our website ( ):
      Connect the electrode and put it in about 20 mL of distilled water; add about 1 ml (half a bulb squeeze) of each of the acid solution and the reactant and swirl in the usual way keeping constant motion. The instrument may or may not indicate STOP as above. If it does not, add a drop of the SO2 Titrant solution. This should make the STOP condition occur. [If it doesn’t you may have an electrode problem read in the next section below how to fix this.] Now add one drop of a concentrated sulfite solution (1-10% is fine) and verify that the STOP signal ends and the PROCEED light illuminates. If this happens, your electrode is probably OK as well.


  24. My SO2 reactant solution and SO2 acid solution have both turned yellow. This happened during the course of a single testing session. The solutions are not out of date. Is this normal or are the solutions no longer usable?

    Thank you,

    1. Jordan,

      Thank you for the inquiry. We also received your voicemail too but thought might be an easier way to respond. Based on what you have told me it sounds like the Acid and Reactant might have been cross contaminated. It is normal if the Reactant solution has a slight yellow tinge but that typically happens over the course of a few years. The Acid should stay clear. The only reason the Acid would turn yellow (or sometimes a lot darker) is if the Reactant solution came in contact with it. The chemical composition of the Reactant is designed to show that yellow color. If you want to send us a photo so that we can verify this, we would be more than happy to take a look at it. You can send it to or reply to this email. The two squeeze bulb pipettes that are provided in the kit should be marked for either the Acid or the Reactant and used only on their specified solution. Best to send us a photo and we can confirm. If they are cross contaminated the Acid and Reactant will need to be replaced.

      Please let us know if you have any other questions.


      1. Hello Taylor,

        Thank you very much for your response. Is there a way to just re-order the So2 reactant solution and So2 acid solution without the titrant? We have an excess amount of that and we don’t want to have extra sitting around and going bad.

        Also, does this call into question any of our recent So2 test results if cross-contamination is the issue.

        Thank you again for your help,

        1. Jordan, the yellow color in your acid solution can also be due to traces of iron. In that case it is probably OK, unless it is a very dark yellow. To verify it’s OK you can do the liquid test: add the usual amounts of acid and Reactant to 20 mL of distilled water, mix and put the SO2 electrode in. If the current is very high (over 1000), the solutions are suspect. If the current is low (below 300 or so) add a drop of SO2 Titrant. The current should shoot up several hundred. If this test passes all is OK.

          1. Richard, the solutions are very dark yellow. I did the test and without adding titrant, it starting to immediately climb to 300 and continue up to around 378, not as high as 1000. Would you suspect that they need to be replaced?

            Thank you,

          2. Yes this sounds like they are bad.

  25. With Reference your SC-300 Pro Kit
    1. What is the benefit of choosing
    either the 10 ml vs. 25 ml burette ?
    2. Once I order the SC-300 Pro Kit
    should I expect to receive it ?
    I live in North Hollywood, CA

    1. Bill,

      Sorry we were unavailable on Friday. Our company closed for the afternoon and had our holiday party. There is no major difference between the two sizes of burettes besides the difference in capacity. We recommend the 25mL burette if you will be doing multiple tests in a row as the larger capacity allows you to run multiple tests without having to refill the burette with Titrant. Our most popular one with our other customers is the 25mL burette although the 10mL is also a good option too. It is just whichever you prefer. The Pro Kits are in stock. I see that you placed an order so we should have your order ready for shipment tomorrow. A tracking number will be sent to you as soon as we make the shipping label.

      Let us know if you have any other questions.

  26. Hello Support;
    I have had my SC-100A SO2 Analyzer for a few years now.
    A couple of months ago the lower part of the display stopped working.
    The unit still works though, it beeps when the SO2 level is reached.
    But I would like to get it repaired.
    Can I purchase a replacement display?
    Can I send it to you for repair?
    Please let me know how to proceed.
    Thank you

    1. Jim,

      It sounds like the LCD screen might have given out if there are missing lines on the display. Typically, when the LCD screen goes out the instrument still works okay and the LCD just needs to be replaced. We can do the repair for you. The unit is covered under a 2 year warranty. If it is out of warranty the cost of the LCD screen replacement is $45 plus return shipping. Whenever you are ready to send it in, you can call our tech support line or send an email to and request an RMA number. They will set you up and let you know how to get the instrument sent back in to us. We can also check out your SO2 electrode for you too if you are interested.

      Our number is 760-494-0597 and select Tech Support when prompted.


      1. Thank You!

  27. My SC-200 has been a good friend for a few years now. This time, however, it keeps going into Lo-Battery mode. brand new batteries keep it going for maybe 1 minute, then lo mode again. I can’t finish a titration. I’ve tried cleaning the battery compartment contacts with a fine file, and of course a different new set of batteries, always the same result. Maybe a short inside that is draining the battery really fast?

  28. In March 2015 you rebuilt my SC300, adding a second input with BNC to RCA jack for the SO2 tests. Last fall (Oct 2016), when I bought my latest reagents, the machine worked fine on Ph, TA and SO2, and Malic. This past July (2017), when I was testing my reds before bottling, the SO2 test did not work. The meter stayed at 0.0 no matter what, but jumped around a couple of times and then stayed at zero. I had a friend test my SO2 on HIS 300 instrument. Right now, mid October 2017, HIS 300 will not power up and he is sending it back to you. I talked with you on the phone about Oct 10th and you said to run the checks listed in your website (“I’m getting strange results in SO2 mode…”). You said you’ve been having trouble with the RCA jack SO2 input and maybe I should try bending the jack a little with needle nose pliers.. I did not so this. The contact is fine. I have done your tests, “TO TEST THE FUNCTIONING OF THE INSTRUMENT:”. Steps 1 through 4 check out fine. SO… I try to check my reds and my whites several times. The meter readout stays at 0.0 no matter how much solution I am entering from the burette. On one test, barely touching the instrument caused the reading to jump form 0.0 to 5.0, than drop back to zero.Sounds like an intermittent in the circuit board or a partially broken internal solder joint? My 300 instrument has not left my test bench, nor gotten wet, nor been dropped. I called your business yesterday and got a recording that Technical would be unavailable for some days. What can I do and soon?

    1. C Stewart,
      Thank you for contacting us. You are correct that technical support is closed this week. I am sorry you are still having issues with the SO2 function of your instrument. Even with Tech support closed, we can still issue an RMA number to you so that you can send it back and we can take a look at it. Tech support might be able to diagnose something over the phone and walk you through some tests when they return but it sounds like that might be too long of a time to wait. You could also try the suggestion that tech support mentioned last time you spoke with them about clamping down on the outer ring of the SO2 electrode to try and get it to have a tighter contact with the port. Regardless, if you would like to send your instrument in this week we can take a look at it and consult tech support, if needed, when they return on Monday.

      If you would like us to inspect your instrument and see what needs to be done to get it back in working order, please send your instrument and all electrodes (we will check the pH function for your too, just to make sure it is also working okay) back to us: 6084 Corte Del Cedro #105, Carlsbad, CA 92011 and write RMA 446 somewhere on the box. We will work to get this returned quickly for you.

      Please let us know if you have any questions.


  29. Hello,
    Our club has started measuring YAN and I would like to know if using different NaOH strengths might be a problem for our TA and YAN calculations.
    I have been using your 0.13 NaOH solution as to your instructions for both TA and YAN. Our club mixes up our own 0.2 NaOH. 1. I assume we can substitute 0.2 into the YAN calculation formula to determine the correct mgN/L in a pH 8.2 sample, is this correct?
    2. Is the any compensation required in determining TA in a 10ml wine/10ml H2O sample when adding a 0.2 NaOH titrant? Also, could a 0.1 NaOH solution be used?
    Thank you

    1. Ian,
      1. yes the substitution of a different normality as you propose is fine.
      2. the same applies here. The general equation is TA ( expressed as g/L of tartaric acid) = (V * N * 75)/S where V is the mL of NaOH titrant, N is its normality, and S is the mL of sample. So you make V = 0.2 (or 0.1 ) and S = 10.

      1. Make N= 0.2 or (0.1) not V? And S does not include the DI in the sample

  30. We purchased the SC aprox. 3 years ago. to test SO2. worked well until the end of last fall. now it flashes 00 and gives no reading at all. I did the paper clip test and nothing. I need this thin ASAP. Is there a repair for this one or do I purchase another interment?

    Ron Hanks
    Hillhaven Vineyard
    Baileyton, Tn.

    1. Ron,
      call us at 408-887-9230 (my cell) if it’s still giving you trouble.
      Thanks, Rich

      1. Hey Rich,
        Didn’t get a response so went ahead & spent somewhere around $300. for replacement. It took the full 15 days to get here. We’re over a month now. Too late, we’d gone ahead & SWAGED it.
        We’ll be checking again soon with the new one. It’s a great tool when it works.
        A bit quicker response wound have been nice, a month seems a bit long, but I do realize I’m not the only customer..

  31. Hi,
    I just tried to use my SC-200 for the first time in several months, and the display is not working properly. The readout is not showing the whole numbers. Unfortunately, I’m discovering this while harvest is coming down on us with extreme force, and you guys are on vacation for the next 4 days! I would immensely appreciate if someone in support can contact me ASAP, as I can’t function fully during harvest without the ability to test pH. Thank you!

  32. In early Aug, SO2 readings did not work. After 25 ml wine sample was
    drawn , acid & reactant solutions added, when electrode was added and
    reading on screen was 0.0. This reading did not change, when the entire 5ml
    SO2 titrant was added , the reading remained unchanged at 0.0.

    1. Andy, check out the FAQ under for information on testing the SO2 performance [go to ]. You may have a bad electrode or a poor connection at the plug. If your plug is an RCA-style (like a phono plug), then sometimes it can be making poor contact at the receptacle on the instrument. Try crimping the outer grounding ring on the plug very slightly to make it just a little oval. This will ensure that the plug’s grounding ring makes good contact with the receptacle. Then try the tests at the link mentioned. If you have further questions contact us at, or call for tech support 760-494-0597. Thanks,

  33. Hi. When measuring SO2, the displayed reading keeps changing. Every time the display updates, the reading drops a little. So when adding the titrant solution, even if the immediate reading is above 50 and the device beeps, the reading will eventually drop to below 50 by itself. Sorry if this should be obvious, but with a constantly changing reading I don’t see how I’m supposed to get an accurate measurement of free SO2?

    1. Thomas,
      first, be sure you keep the solution around the SO2 electrode stirred or swirled, as readings will drop more than normal if you don’t.
      second, NEAR the titration’s endpoint, it is normal for the reading to rise above 50 briefly then drop below.
      third, at the TRUE endpoint, the reading will go considerably above 50 (e.g. 150 to 300 or more) and will remain there for 15 seconds (but keep in mind the first point!)

      That is why the manual says to take the endpoint as the FIRST drop of SO2 Titrant that causes the STOP condition to persist for 15 sec
      (20 beep).
      All best,

  34. Hi. I recently purchased a SC-300 and have tried measuring Free SO2 in a commercial wine. However, I can’t seem to get a stable reading once the SO2 probe is in the wine (after adding reactants etc), when stirring the reading constantly drops. The reading may hit a stable value for some seconds before continuing to drop. Is that to be expected?


  35. Greetings, I have a question regarding cleaning and maintenance for the SC-300 probes. I have generic pH and ORP electrode cleaning and storage solutions for our pH meter. Is this sufficient for the SO2 probe as well? Any other recommendations specifically for the SO2 probe maintenance? Thank you

    1. Jamie,
      there is no need to store the SO2 electrode in a solution. When done using it, you just rinse with distilled water and let air dry. There is no particular maintenance required; as long as the Pt wires are clean and shiny they should work fine. If you observe wine residues clinging to the wires, remove these by soaking the electrode 2-3 minutes in your SO2 Acid solution, then rinsing with water. If need be you can remove adherent residues by gently scraping with the blunt end of a knife.
      -Rich Sportsman

  36. Hey guys, I gotta say that I love my SC-300! Very handy tool. But recently I have developed a situation on my display. I have two decimal points! pH reads as 5.0.1 instead of 5.01 It started when I recently changed batteries and I know it doesn’t really affect anything, but it is annoying! Any thoughts? Thanks for your time and attention. -Marty J

    1. Martin,
      Sounds like a connection issue with the LCD screen. If it doesnt really bother you, it is probably okay and you can continue to use the instrument normally. Otherwise we can replace the LCD screen for you for $45 plus shipping. If you would like to get it replaced, please call our Tech Support Line and they can assist you with the return process. 760-494-0597

  37. When will you develop a video for testing YAN ? I think it is very important to know if the yeast will have sufficient nutrients to fully ferment all the sugars in the must.

    1. Aldo,
      The YAN video is now up. Please let us know if you have any questions.

  38. I am beginning to feel old!
    You suggest storing the pH sensor in a 3M solution of KCl
    I have no problem with the reason for that but have recently been asked ‘Why 3M? Why not 1M or 2M?’
    It is about 50 years since I had to struggle at school with moles and Avogadro etc. and the best I could offer in reply was ‘Because it works well’
    Is there a better answer?

    1. Trevor,
      the reference electrode in most combination pH electrodes, like ours, is a silver/silver chloride (Ag/AgCl) electrode. This electrode is supposed to maintain a constant potential against which the pH electrode’s (i.e., the glass bulb sensor) changing value is measured. The Ag/AgCl reference electrode can be in a solution of KCl of various concentrations but typically 3 M is used, as in ours. So to maintain the reference electrode at its correct potential it’s important to keep the reference junction (which can slowly leach out KCl through its frit) in that same concentration of KCl when the electrode is stored.

  39. I have a SC-300 that has separate connectors for the PH and SO2 probes, is it necessary to disconnect the probes when changing between the PH test and the SO2 test?


    1. Dale,

      If you have two connectors on your instrument, you do not have to disconnect the probes when changing between the modes.

      Please let us know if we can help in any other way.


  40. Hello,
    I typically make 10-15 gallon batches of red wine. If the DO test results tell me to add O2 (during some early phase of wine-making), the practical difficulty I would then have would be how to add this O2.

    Thanks for any advice on addition of O2 in small batches.


    1. Hi,
      you don’t generally need to add oxygen to your wine after the first few days of fermentation. If you need a low level of dissolved oxygen you can use something like a $10 aquarium pump (with a cotton plug to keep out particulates) for several minutes to bubble air through, then mix well and reassess the DO level.

  41. Generally, procedures to determine TA specify that CO2 be eliminated from the sample. Most call for a microwave step. The Vinmetrica procedure does not call for any step to eliminate CO2. Why not? Does that add to inaccuracy?

    1. I recommend that the sample be agitated or shaken in a closed container until degassing ceases, if significant CO2 may be present; also, drawing a vacuum on the sample for about 1 minute may be done. I don’t think I would use a microwave for this purpose; volume losses and some volatile acids evaporating may contribute to error. We should add this to the manual, which only talks about use of a blender with musts (which would achieve the same result )

  42. Hello,

    I have a Vinmetrica SC-100A and It worked very well untill yesterday. When I turn the device on without the SO2 electrode connected, it shows a value of zero and the green proceed light is on. This is normal. When I connect the electrode , I get a high value of around 700 and the red stop light stays on. It also keeps beeping and this doesn’t stop. I have never had this before. Before the problem, the reading WITH the electrode connected was ZERO. Is my electrode defect? Thanks you for answering. Paul Vermeeren, Belgium

    1. Paul, check to be sure that the wires at the end of the electrode are straight and not touching each other. Otherwise it sounds like the electrode may have become defective. If it is less than one year old it is under warranty and will be replaced. Contact us directly at for more information. Thanks.

      1. Sir,

        Thank you for your answer. I have checked the 2 electrodes and they are in the right position and not court-circuited. The electrode is likely to be
        defectuous as you stated in your answer.

        Greatings from Belgium

  43. Should I store my reagents (for SO2, pH & TA) in a fridge to prolong their lives?


  44. Hi there!

    Purchased a SC-300 Analyzer about 2 years back. Having issues with it…I was wondering if we can purchase parts for repair? I would probably need the Main/control Board & keypad overlay for the unit.

    1. Hi Angelo,
      Sorry to hear you are having trouble with your instrument. There could be one of several things happening, I suggest giving us a call at (760) 494-0597 and then press “2” for Tech Support. We can go over what might be causing your issue and see if it can be resolved over the phone.
      Happy Testing!

  45. I have a couple of questions regarding the SC-300: For the acid reagent, can I use (1+3)sulfuric acid instead of the 2M HCL acid you sell? Also, can you use iodine instead of iodate as titrant? Thanks

    1. Hi Ernest,

      Both 1+3 sulfuric acid and iodine will work. However, the endpoint will be blurred and may not be as finite as if you were using the reagents that we sell specifically for the kits. We do not recommend using other reagents as we are unable to verify their quality and in turn cannot support the results given. If you would like to go ahead and give it a try you are more than welcome to. Those reagents should not damage any of the Vinmetrica equipment.

      Happy Testing!

  46. I don’t see any calibration videos or help on the 100A I need help.

    1. Hi Steve,

      The SC-100A uses an SO2 electrode which does not require calibration. The “How-To” video for calculating sulfite can be found here. Please feel free to contact our tech support line at (760) 494-0597 if you have any further questions.

      Happy Testing!

  47. Hello – I am wondering if my pH and TA probe is working correctly. Testing pH, the meters readings will swing back and forth. All of a sudden, the reading will drop significantly and start working towards the pH of the solution again. I have to calibrate more than once, frequently. I did purchase new regents. Is there a shelf life for the probe?

    Thanks – Bill

    1. Bill,

      It is hard to diagnose this issue over the phone as it could be any number of things. I suggest that you call Tech Support, if you havent already done so, at 760-494-0597 and select Tech Support when prompted to. Make sure to have your unit when you call in as there are several things they will walk you through.


  48. I am also wondering if there is an additional step involved that will allow me to measure not just the free SO2, but the total SO2 levels in wine batches? I heard I needed to order 1N NaOH to perform this test, but don’t see any information on your site helping me learn these steps.

    My Vinmetrica Equipment: I own the SC 300, newer model with two probe connectors on top.

    Mike G.

    1. Mike,

      There is an additional step to determine the Total SO2 in your wines. And you are correct. You will need the 1N NaOH solution. The instructions on how to do this are located towards the back of the manual that was included in your kit. We will make the instructions available on our website as well. Thank you for the tip!

      Please let us know if you have any questions about this procedure.

      Take Care

  49. Could you please post videos and instructions on your website, and on YouTube concerning how to measure residual sugar in wine using the supplies you sell. I would like to order, but don’t have information on how to use the supplies to do this.

    Also, I would like to measure alcohol content of finished wines on batches I’ve misplaced initial SG readings from must. Do you have a way we can do that too?


    Mike G.

    1. Mike,

      The instruction manual for the Residual Sugar Assay was sent to your email a few moments ago. Please review and let us know if you have any questions.

      We are working in developing a method for alcohol testing but do not have anything available yet.

      Thank you

      1. Hello Richard,
        I’m also interested in the alcohol measuring solution.
        Do you have an update on your progress?

        1. John, we are still working on it. Stay tuned. Thanks

  50. Why should I buy my chemicals from you when they cost the same at more wine and they ship for free?

    1. William, there is no difference in the product. If you buy from us directly it does help us of course.

  51. In reading the SC 100A Manuel, Version 2.1c page 6 there is an equation of 64 * V * N * 1000 divided by the equation of 2 * S. My question is “how or where does the 64 come from?”


    1. Linda,
      in the equation, 64 is the formula weight (or molecular weight) of SO2.

  52. We have now for the second time messured total SO2 in our wine. This time we used a wine that has been tested by a lab. They got 86 mg/l total SO2. Our measurment using your instructions showed only 11 mg/l total SO2. So what can be wrong?

    1. Anders, It is not expected to get a much lower number than a reference lab, and the value of 11 does not seem correct. It is hard to know what might be wrong. It is important that the NaOH pretreatment is done correctly. So please be sure that the 1 N NaOH used in the procedure is reasonably new and of the correct concentration. When you add it to your wine, the sample should become dark blue in color, and if you check the pH it should be above 12. If you continue to see such low numbers, please contact us directly at

  53. While utilizing my SO2 probe, it has recently stopped reading shortly after titration starts, and just starts flashing “00.” I have changed batteries etc., nothing works. Is there anything I can do or is the probe shot?

    1. Ryan,
      it is normal for the SO2 probe to show a small value initially and then drop to 0.0 during the procedure. When you approach the endpoint, you should begin to see numbers rise and fall briefly, then increase to a higher level and stay there when you reach the endpoint. If you suspect something is wrong with the probe or other parts of your kit, please check the tests described under the FAQs at // Contact us at info@vinmetrica if you have any questions or unresolved issues.


  54. We have been using SC-200 for two years and are very pleased with the Equipment. However, today we measured total SO2 according to your instructions, with a very surprising result. It was much lower than the amount SO2 we have added during the winter.The grape is Rondo known to ”eat” sulfite. But how can it disappear? Has it been bound to compounds in the wine that we have racked of? Or do you have any other solutions?

  55. I have ancient equipment for testing FREE SO2 used just before bottling. I wasn’t getting any reading at all and thought my metabisulfite was old although it was purchased only 3 months ago. Foolishly I added an additional amount and still got absolutely no reading at all. I received an SC-100A today and was horrified at the reading — 68%!! How can I save my 55 gallons?

    1. Maryl,

      There are other factors, such as pH, that can help determine if your wine is okay or not. The sulfite levels in your wine will gradually start to decrease. Check your levels again in a few weeks. Your wine may be okay. You can always call our tech support line if you need further assistance. Just call 1-760-494-0597 and select Technical Support.

  56. Vinmetrica sc-300//
    I recently checked the PH accuracy with the PH 3.49 solution and my result was 3.59. I began calibration with the 4.01 reference solution and the result was 4.11, calibration was completed. I then calibrated with the 7.00 solution and the result was 7.90, calibration was completed. I re-checked the accuracy with the PH 3.49 solution and the result was 3.44, 0.05 variation. My question is, if the accuracy is off +- a variable, does that apply also to the TA results? and why?
    Thank you

    1. Ray,
      the pH measurements on an SC-300 should come in at +/- 0.02 if temperature is controlled; a little more error may be expected if temperature is significantly different from 25C (78F). You should be able to hit the target value of 3.49 within 0.03.
      In addition there can be be some drift that takes more than a few minutes to settle down. In your case you may want to re-check the calibration after 10 minutes.

      Note: You can check your calibration with a second reference, that is, a saturated solution of cream of tartar (potassium hyrdogen tartrate). See “cream of tartar test” in our FAQ under

  57. G’day Doc
    I purchased the SC200 approx. one month ago & had it shipped to South Australia. In the middle of vintage at the moment and it works like a charm. However I notice that you don’t supply the “special solution” to keep the pH electrode in the storage bottle wet. I can see the time rapidly coming when the storage bottle will need to be topped up. It seems pretty silly to ship a tiny amount of solution all the way to Oz where the cost of postage will be more than twenty times the cost of the solution. Therefore could you possibly send recipe details so that I can keep my tip moist !!
    Regards Peter R.

    1. Peter,

      We are glad to hear you are enjoying our equipment. We do sell the replenishing solution for the pH electrode on our website. It is called the pH electrode Storage Solution and can be found under the Individual Reagent page. We understand the cost involved with shipping this solution all the way to South Australia. We are still trying to establish a distribution agreement with a company in Australia but have yet to find one.

      The solution that the pH electrode is stored in is 3M KCl in our pH 4 buffer (or any slightly acidic medium). This is a common recipe for most electrode storage solutions and can probably be found at a company that produces electrodes in Australia. Theirs will most likely be the same as ours. I just typed this in a search and several companies do come up. Please let us know if you need any help finding it or if you need any other information. We are here to help.

      Take Care,

  58. Dear Mr. Sportsman,

    Thank You for your meters they are very easily helping me to measure SO2, PH, TA and finally MLF in my wines. I have SC 100 meter old version can i calculate in future with some upgrade the concentration of malic acid by SC 100 or it will be impossible.
    In the manual of SC-50 MLF is noted that, for updates I must check FAQ on your web, but I cannot find information about updates of SC100 there.
    My second question is that, I’m buying all your meters throe other web sites and reason is that I’m from Caucasus Georgia. I have a shipping address in USA. From this address it is easier to ship goods from states to Georgia it is chipper and quicker, but Paypal doesn’t give possibility to do it because of different countries in billing and shipping addresses. In other web sites it is possible. Question is: How I can buy from you by credit card?



    1. Beka

      We are please to hear that our instruments are being used all the way over in Georgia!

      You will not need to upgrade your older style SC-100 to use it with our SC-50 MLF Analyzer. Just be sure to read the latest version of the SC-50 manual on our FAQ page (// ) so that you are running the most updated procedure.


    2. Hi Beka,

      Yes we may have a method to purchase with a credit card that is not necessarily linked to an address in the US. We will be updating the website in the next couple of weeks, so it should be possible.


  59. I am interested in buying Vinmetrica SC-300 SO2 & pH/TA Analyzer plus spare reagents for our small vineyard with 1,000 vines. Main problem – I am in England!! Do you ship to the UK and how would I go about ordering and paying (my credit card is in UK pounds sterling)

    Also do the meter measure in parts per million or in ml/litre?

    Liz Robson of Kingfishers’ Pool Vineyard. Leicestershire

    1. Liz, Thank you for the inquiry. We do ship the the UK, but we also have two European Distributors. One in Sweden and one in Denmark. Their information is listed on our home page at the bottom on the Distributor link. There are links to their websites there.

      We can also ship to the UK. You can purchase through our website but during our secure checkout process there may be some issues with having to enter your billing zip/postal code. We can work with you if there are issues and send you an electronic invoice to pay. If you would like more information please email Taylor in Sales at

      Our instruments measure in ppm.

  60. Hi; How important is the expiry on the SC-100A reagents? I have three unopened bottles that I bought from MoreBeer 8 months ago, but the expiry date is 6 months from invoice date. So how long do reagents actually last once opened?


    1. Hi Chris,

      While we guarantee our reagents for 6 months, the SO2 reagents (found in the SC-100A and SC-300) typically last much longer. We have used reagents that were over two years old (which were properly capped and sealed) which still gave accurate results. We keep to the 6 month policy because reagents can be degraded over time if left uncapped or if contaminated by other reagents. In addition, the TA Titrant (found in the SC-200 and SC-300) becomes ineffective over time, as a result of it slowly mixing with CO2 in the air. If you are not sure about your SO2 reagents we have a procedure for verifying their effectiveness here. Hope that helps.

      Best Regards,
      Richard W.

  61. Is your M/L tester still in beta?

    1. Dave, yes, we are still in BETA testing for the Malic Test device. We are estimating that it will be complete in mid November. Please keep checking the website as we will make updates there when they come available. Thank you

  62. I am considering purchasing the Pro kit. Do you have it in stock? I have no way of seeing the product in action before I purchase so wondering what is your return policy? thanks. Ted

  63. I would like to chat over the phone if you get a chance

    Thanks Steve

    1. Steve,

      We are here Monday – Friday 9am to 5pm. Please call 760-494-0597 when you have a chance. We are happy to help you with any questions you may have.

  64. Thank you.

  65. I recently purchased a sc100a. I tested some new wine and the display went from 0.0 to 1999 after adding the first few drops of titrate. What does this mean? Help!

    1. Hi Bob, This occurs when your wine has less than 2 ppm Free SO2. You are going to want to add some sulfite to your wine.

  66. Please advise where I can get You SC-300 in Australia and the price including postage

    1. Hi George,

      Currently we do not have distributors in Australia but we do ship to Australia if you purchase from us directly. Check out our international page here. We ship the acid solution in slightly different sized containers to abide by international shipping laws. Shipping charges usually vary depending on where in Australia, but they are usually are around $100 US dollars via FedEx. So the total price for the SC-300 with shipping would be close to $452. Hope it helps, feel free to call or email us, our number is 1-760-494-0597 and email is

      Best regards,
      Richard W.

  67. How does one measure total SO2 using your sulfite analyzers?

    1. Hi Richard,

      Total SO2 can be measured by purchasing 1 N NaOH. We offer it on our website here. Instructions for doing the Total SO2 test are included in the Vinmetrica SC-100A and SC-300 Kits.

      Best Regards,
      Richard W.

  68. I would like to make a good size purchase from your company and I have been checking around for some time looking for coupons. Can you direct me to a place to find any? Thanks

    1. Hi Michael,

      Please contact us by 760-494-0597 or email if you are interested in purchasing a larger order from us.

      Best regards,
      Richard W.

  69. Hi,

    Do you have a distributor in Australia and, if not, could you ship to Aus?



    1. Hi Rob,

      At the moment we do not, we are working with a couple of companies to supply to Australia. We currently can ship to Australia but we must send a more concentrated lower volume solution to abide by international shipping rules. To purchase our international products, with the more concentrated acid solution, hover over the ‘products’ menu item, then click ‘international’. Hope that helps, feel free to call us at anytime if you have any further questions.

      Richard W.

  70. The kit calls for using DI water. Will using distilled water skew the results? Where would one find DI water?

    1. Craig, distilled water is fine. “DI water” stands for deionized water, which is the same as distilled water for almost all applications, including this one.

      1. Thanks. I am getting some crazy results when trying to test for SO2. I had my wine tested at a reputable lab and it was around 20 ppm. I adjusted it with 10% solution up to 28 ppm and tried to test. The reading was low and close to zero as I started to add the Titrant. after less than 1 mL the values jumped up to numbers in the high hundreds and thousands. I was adding single drops and not going fast so it seem suspicious. Additionaly it indicated around 20 ppm which I know cannot be true. I will try to Hot probe technique described but am thinking I might have had a defective probe shipped with the unit. Any suggestions or comments. I really need to get an accurate SO2 reading because I am getting ready to bottle and want to get my wine close to 0.5 molecular. Thank.

        1. Hi Craig,

          I would check a couple of things. First when adding 10% potassium metabisulfite solution, make sure the solution is relatively fresh and has been capped and sealed well. The solution will oxidize over time and will lose its efficacy. Second, the unit has a filter to decrease noise from 0.0 to 5.0 nanoamps, this results in the device sometimes jumping to a high number. The SO2 endpoint is reached by a sustained beeping signal for at least 20 “beep-beeps”, the red stop light indicator staying lit and the current on the display peaking anywhere from 200-700 nanoamps. The signal does generally go down with time as the free iodine becomes oxidized. By continuously swirling the solution (or using a magnetic stirrer) and adding drops slowly as you have done should still result in a very accurate reading. Third, when making a sulfite addition, much of the sulfite will become bound. When sulfite becomes bound it cannot equilibrate into molecular SO2 and the bound sulfite is not detectable by the unit when measuring Free SO2. This results in readings that seem lower than what seems correct based on the amount you added. I recommend completely stirring your wine vessel after your sulfite addition and measuring the SO2 a few hours later. Stirring ensures you are getting a homogeneous wine sample and an accurate SO2 reading. When mixing make sure to use a very clean stirring rod or mixing apparatus to minimize bacterial contamination. Thanks for the question.


  71. In running the SO2 test the amount of acid and Reagents that is put into the wine appears to vary each time by a little amount more or less due to how much the bulb takes in. Does this matter or is there an exact amount that I should be putting in the wine to make the SO2 test more accurate. I love the product, just want the most accurate test possible.


    1. Hi Mike,

      The Acid Reagent and Reactant solution are more concentrated than the SO2 Titrant. These solutions help the SO2 Titrant become chemically active. If you look closely at the transfer pipettes you will see gradations on it measuring from 0.5 mL to 3.0 mL. As long as the volume you are adding of the Acid and the Reactant is within 1.0 to 3.0 mL you should be getting very accurate results.

      The key to accuracy and precision is with adding the SO2 Titrant. Make sure that the syringe you use does not have droplets on the tip or adhering to the outside of the syringe. These droplets could fall into your wine titration vessel and result in inaccuracies of measurement. The same goes if you are using a burette.

      By using a burette you can increase your precision and resolution quite a bit. If you are interested you can purchase the Deluxe Lab Accessory Kit from us which you can find under the ‘Products’ tab and click on ‘Glassware & Lab Equipment’. This kit includes the Magnetic Stirrer, the Lab Support Stand, the Double Burette Clamp, the 10 mL Glass Burette and the Vinmetrica Electrode holder; all of which can be purchased separately. Thanks for the question!


  72. It does not appear thet the measurements are temperature compensated. Is this the case and do you have to adjust the math for the tempereature difference?

    1. Graham,
      I assume you are talking about the pH electrode, as the SO2 electrode is largely unaffected by temperature. If the temperature varies from 68 to 84 degrees Farenheit (20-30 degrees Celsius) there will be little change in your pH value. If you have some concern about your results, make sure that the temperatures of the Reference Solutions are close to the temperature of your samples and then calibrate the pH electrode using those references. When measuring TA your pH electrode should largely not be affected by temperature either.


  73. When using your calulation to get TA I get numbers like 3.3. Titrate volume x 2 I see TA numbers like .048. Titrate volume x .015 What is the difference.

    1. Joe,
      Our calculation reports values in grams/liter expressed as tartaric acid. Some winemakers prefer % wt/volume tartaric acid, which you can get by simply dividng our value by 10. Others prefer to use acidity in units of eq/L, which does not assume tartaric acid.
      Let’s say you do a TA and it takes 3.4 mL with our kit. If you use our calculation (i.e., multiply by 2) you get 6.8 g/L tartaric acid. That is the same as 0.68% tartaric acid. To get eq/L of acid, multiply the volume of TA titrant used by its normality (0.13) and divide by the volume of wine taken (i.e., 5 mL if you use our standard method. ) So in this case the value is 3.4 x 0.13 divided by 5, or 0.0884 eq/L.

      Thanks for posting!


  74. Please provide an example of the math for the sc-100 free…
    Your example shows 20 x V. How is V expressed say I use 5 ml is this 20 x .5 = 10 ppm?? and 20 X 1ml = 20 ppm??

    1. Terry,
      V is expressed in mL; if you used 5.0 mL of SO2 titrant then the calculation is 5.0 x 20 = 100 ppm SO2. If you used 0.5 mL it is indeed 0.5 x 20 = 10 ppm and if you used 1.0 mL it is indeed 1.0 x 20 = 20 ppm.

      All best,

  75. I red you have distributor in Sweden. This could be very interesting for me. Can you give me details of the distributor?

    1. Our distributor is Gutevin,, contact Mr. Lauri Pappinen

      Many thanks,

  76. Question? Once I calibrated the pH electrode, could I continuously test all my carboys one after another PH & TA & SO2 without recalibrating it. Or do I need to only do all my carboys PH & TA only without disconnecting the PH electrode so I don’t lose the calibration.

    This is a great product, every wine maker should have your product.

    1. Joe,
      you should only need to calibrate the instrument about once a day. It should keep its calibration whether you switch electrodes or not. It might be advisable though to do all the pH/TAs at once if not inconvenient.
      Thanks for your comment.

  77. Mr. sportsman,

    Thanks for wonderful products. I am intending to by SC 300, but I live quite far away, in Montenegro in Europe. Therefore I would appreciate if you could give more info about maintenance of your products. I am particularly interested about durability of electrodes. How often the electrodes must be replaced? Do you ship to Washington DC?

    Thanks a lot and wish you all success in business and private life

    1. Yes, we ship to Washington DC. We do have distributors in Denmark and Sweden, if that is more convenient, feel free to call or email us, our contact info is at the bottom of this page.

      The SO2 electrode should last a very long time as long as the contacts are not physically damaged. We guarantee this electrode for a year but we still use a SO2 electrode that has been working for nearly two now, we expect it to last many more. After you are finished using the SO2 electrode just simply rinse this electrode with distilled (or de-ionized) water, and let it air dry. No further maintenance necessary.

      The pH electrode is also guaranteed for a year. Typically, pH electrodes can last anywhere from a year to three years depending on how heavily they are used. Even if not used at all pH electrodes degrade with time. The pH electrode is more delicate than the SO2 electrode, by nature of its glass bulb membrane. After you use the pH electrode, you must rinse with distilled (or de-ionized) water and dry off the electrode by very lightly blotting the electrode against a paper towel or tissue. Then place the screw cap on the body of the electrode and screw on its storage solution container, with the pH electrode’s glass bulb membrane in light contact with the sponge inside the container. This guarantees the pH electrode stays wet and will continue to function for later use. Be very gentle with the pH electrode and be careful not to scratch the glass bulb membrane. If you use a magnetic stirrer make sure the electrode does not bump against the stir bar while it is spinning, it could destroy the glass bulb membrane.

      The pH electrode operates by using a thin glass bulb membrane which houses an electrode,that measures the change in concentration of H+ in the wine sample versus the pH within the glass bulb electrode. A silver/silver chloride reference electrode is embedded with a gel membrane that allows the flow of ions through it. This gel membrane can be clogged because of the many large molecular components in wine (like proteins and polymers), this usually results in the pH electrode responding slowly or erratically.

      If you are suspicious that the pH electrode is dirty, then let the electrode soak in a 0.1M HCl solution for 15 minutes (you can make a 0.1M HCl solution from diluting our 2M HCl SO2 Acid solution 19:1 in distilled or de-ionized water), then rinse with de-ionized water and return to the storage solution for two hours. Then check the pH electrode again. If the pH electrode still isn’t working and you think you have grease or oil on the pH electrode, put the electrode in a mild soap solution and stir gently for one minute. Then rinse with de-ionized water and try using the pH electrode again.

      For either electrode we sell replacements if and when you need them at a reasonable price.

      Thank you for your questions, I hope you find the information provided useful.

      1. Thanks a lot for info. I will get back to you by email.

  78. are your meters still made in the usa?

    1. Our meters are assembled in the USA, but to use the “made in the USA” tag you have to have essentially everything sourced from the US. Obviously that is hard to do in this day and age, when practically every electronic component is made overseas. Our new meters use circuit boards that are made in Colorado and populated here in San Diego. The enclosure, LCD display and most if not all electronic components are from Asia. The electrodes are provided by a U.S. firm but I believe they are actually made in China.
      Plasticware and all reagents are made in the USA. Final assembly and testing of the instruments is done here in San Diego.
      Our first instrument, the SC-100, was made mostly of parts from the USA (except for the electronic components i.e. resistors, capacitors and ICs, and the LCD unit) and assembled, tested, and packaged also here in San Diego.

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