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 



Frequently Asked Questions

SO2 Questions

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

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.

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 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.

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, note that 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 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 (vitamin C) test located on our website

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.

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. 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.
2. 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 signal 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.
3. If values appear to drift, leave the electrode in the pH 4.01 reference solution for 30 minutes.
4. 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.
5. If the displayed pH value is within 0.5 pH units of the target, but the CAL light fails to flash in the expected “ready-to-calibrate” manner, you can try the “force calibrate” feature (available in firmware 3.0.6 and higher, described in the manual under “Calibration of pH”).
6. 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 7-12, 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.
7. 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.
8. 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.
9. 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.
10. 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.
11. 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.
12. Some other tricks: protein deposits can be removed by soaking in 1 % pepsin in 0.1M HCl for 15 mins. Inorganic deposits may be removed by soaking in 0.1M tetrasodium EDTA solution for 15 mins. Grease and oil deposits may be removed by rinsing electrode in mild detergent in methanol solution.

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 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). For more information about temperature effects on pH calibration, see here.


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.

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 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.

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.

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.


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.

How stable are the reagents?

The SO2 reagents and the pH/TA reagents are all warranted to last for 6 months, and we now give an expiration date that should be a minimum of 12 months from purchase. To ensure best stability, always store tightly capped. And of course, the reagents will last much longer if not cross-contaminated with each other!

How can I check the accuracy of my reagents?

It’s rare that the SO2 reagents go bad, but if you are concerned about it, here is a method to check your SO2 reagents with vitamin C. Ascorbic Acid test

And here is how you can check the TA titrant: KHP test

To check the accuracy of your pH reference solutions and calibration:

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 (AKA potassium bitartrate) 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 reagent grade potassium bitartrate, also known as potassium acid tartrate or potassium hydrogen tartrate. Call it KHT for short.
b. place about 1/4 teaspoon of KHT in 20 mL of distilled water. Mix well for about 2 minutes. 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 off the solids from the liquid.
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.


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

MSDS Sheets

SO2 Titrant


Acid Solution

pH7.00 Reference

pH4.01 Reference

TA Titrant


Boost Juice

Malic Acid

Reaction Buffer

Buffer Solution


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

94 thoughts on “Support

  1. 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,

  2. 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?


  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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.


  8. 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.

  9. 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 )

  10. 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

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


  12. 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!

  13. 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!

  14. 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!

  15. 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.


  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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

  21. 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.


  22. 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?

  23. 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.

  24. 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

  25. 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,

  26. 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.


  27. 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.

  28. 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.

  29. 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

  30. 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

  31. 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.

  32. Thank you.

  33. 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.

  34. 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.

  35. 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.

  36. 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.

  37. 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.

  38. 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.


  39. 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!


  40. 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.


  41. 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!


  42. 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,

  43. 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,

  44. 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.

  45. 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.

  46. 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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