Frequently Asked Questions


What is the Warranty/Return Policy?

Vinmetrica’s Return Policy:

Customers are entitled to a full refund less 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.

Warranty Information:

The SC-100A, SC-200 and SC-300 units each come with a 2 year warranty. Any electrodes come with a 1 year warranty and all plastics, lab equipment and reagents come with a 6 month warranty.

While the reagents only have a 6 month warranty (this is because we do not know how the reagents are treated once they leave our hands), with proper care most of them should last at least two years. All reagents have a use by date clearly printed on the labels.

Vinmetrica’s warranties and liabilities are:

1. Instruments, electrodes and non-reagent accessories are warranted against defects in workmanship for 24 months from date of purchase. The reagents are warranted to perform as described in the manual up until any stated expiration or “use-by” 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!

Part of the LCD display on my analyzer has gone out and I can no longer read full digits on the display. Can you repair my unit? Or do I have to buy a whole new one?

If there are segments of the LCD display that no longer illuminate or whole numbers have disappeared there is probably an issue with the LCD screen itself. Most often, a replacement LCD screen can be installed and this fixes the issue. Typically, when the LCD screen goes out the instrument will still work okay.  If this has happened to you, please call or email our tech support for an RMA number and we can give you additional instructions.

Sometimes, although rarely, there are other issues with the circuit board that cannot be fixed. If this is the case, the unit will need to be replaced.

If a repair/replacement is needed and the unit is out of warranty there are costs associated with these services. The units are covered under a 2 year warranty. If it is out of warranty the cost of the LCD screen replacement is $75 plus return shipping.

Should I choose the 10 ml or 25 ml burette in the SC-300 Pro Kit or the Deluxe Lab Accessory Kit?

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. The 10mL burette is slightly more accurate as the gradations on the burette are finer so you can read it to one additional decimal point.

The most popular is the 25mL burette although the 10mL is also a good option too. It is just whichever you prefer.

If you think you may want to do the ABV Assay or the RRS Assay in the future you may want to purchase your Pro Kit or Deluxe Lab Kit with the 10mL burette as those two assays require the 10mL burette in order to get accurate results. Or you can simply purchase an individual 10mL burette at a later time.

The connector on my analyzer spins freely… is that normal?

If the connector itself is loose and can be pulled out of the housing then the instrument will need to come back to us for repair (if it is still under warranty). If it is out of warranty, please call us and we may be able to direct you on how to fix this.

If indeed you have the older RCA plug (gold connector), 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. More information about this can be found on our Troubleshooting Guide on the Support tab.

How many tests can be performed with the SO2 and pH/TA Reagents that came with my SC-300? (Or SC-100A or SC-200)

The SO2 reagents included in the SC-300 should allow you to perform about 50 SO2 tests

The TA Titrant should be enough for about 30 TA tests.

The pH Reference Solutions should be good for an unlimited amount of tests. If you are careful enough and rinse your electrode well, you can simply place the pH probe straight into each of the reference solution bottles to calibrate. Make sure the solution is mixing at all times.

All these reagents have a 2-year shelf life.

Can I use distilled water rather than DI water?

Distilled or DI water are okay to use. Make sure they are fresh too.

Click Here to Find One of Our Distributors in Your Area

Our full distributor list can be found on our “Find A Distributor” page.

pH/TA Questions

I want to use the SC-200 to test for an acid other than Tartaric Acid. Can I test the pH and Lactic Acid level in beer or other beverages?
Yes! The SC-200 or SC-300 can be used to test beer, cider or any other beverages, you just need to know what Acid you’re testing for.
For example, you can do pH and TA on beer with the SC-200 or SC-300.
The pH is independent of the beverage or whatever solution it’s measuring.
The TA is also; it’s just a matter of how you calculate the final answer.   Wine TA is usually reported as tartaric acid but the titration actually measures acidity as equivalents per liter (eq/L). If you assume the acid is mostly tartaric (true for wine) then you use the conversion factor for tartaric acid (75), as we do in our kit.
For measuring the acidity levels in a sour beer you would use the factor for lactic acid (90). So you could just convert as:          g/L lactic = 90/75 * g/L tartaric. To determine the conversion factor for the acid you are looking for, simply look up the molecular weight of the acid. The molecular weight of Lactic Acid is 90, so that is why we used it in the equation above.

I measured the pH of distilled water, expecting it to be 7.0, but instead it came out way different! Is something wrong with my equipment?

Don’t frustrate yourself trying to interpret the pH of pure water.  In principle, very pure water should indeed have a pH of 7.0, but usually it is 5 to 6 because atmospheric CO2 dissolves readily into the water to produce carbonic acid.  Some deionizers will produce perfectly pure water that is nevertheless slightly alkaline, pH 7.5 – 8.  Check your pH calibration instead with cream of tartar.

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?

After calibrating the unit in both the 4.01 and 7.0 solutions in my house, I go out to test my 52 degree wine tank. Is that okay?

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 do this by storing your pH calibration solutions in the same room as your wine tanks.

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.

The ability to test pH with ATC may be an available feature in 2021. Keep an eye our for any announcements in our newsletters.

Additional Information:
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


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. Does this skew my final TA results?

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.

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.

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.

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?

A better way to test the validity of pH calibration is to measure the pH of a saturated solution of cream of tartar.

  1. 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.
  2. Place about 1/8 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.
  3. Decant or filter the solution off the solids if possible.
  4. 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. We usually are OK with a value between 3.50 and 3.60. Discard after 24 hours

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 the water, 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.

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?

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.

I recently purchased the SC-300 and forgot to screw on the pH storage bottle and probe was left to dry for a couple days. Is my pH probe ruined? If not, what should I do?

Place the electrode back in the storage solution as soon as possible. It may come back to life. Soak the probe in the storage solution (but make sure this solution is clean and clear) for a few days and then try and calibrate it and see what happens. If you do not have fresh storage solution you can soak it in the pH 4.01 reference solution until you are able to get fresh pH electrode storage solution.

What’s the best way to add acidity, and how will that change the TA?

The best way to add acidity is: slowly and carefully! As discussed in this BLOG post, add half the amount you think you need, then re-check pH and TA to see where you are.

When you add acidity with tartaric acid (as we recommend) then the TA just goes up by the amount you added (in g/L).  As we’ve discussed in the above mentioned blog post, the decrease in pH that this effects depends on the TA (buffering) ability of the wine.

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.

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

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.

Can I conserve SO2 or TA Titrant by placing unused solution back into its respective bottle?

Yes! You can do this to save your Titrant but always make sure you are putting it back in the correct bottle. Make sure you do not cross contaminate any of the solutions. If you are careful this is a great way to preserve your Titrant.

My SO2 reactant solution and SO2 acid solution have both turned yellow or burnt orange. What happened?

This is most likely an issue with cross contamination. If they are cross contaminated the Acid and Reactant will need to be replaced.

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 .

It is very important that 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.

How do I know if I am purchasing the correct termination for my SO2 electrode?

We have created this handy Electrode_Guide to guide you in selecting the correct SO2 electrode. Remember, you are selecting the SO2 electrode termination so find the picture of the instrument that matches your instrument and select the electrode that matches up to it.

What are the SO2 Acid, SO2 Reactant, and SO2 Titrant made of?

Our SO2 Reactant and SO2 Titrant are proprietary solutions. The SO2 Acid Solution is 2 molar (2M, or about 6% by weight) hydrochloric acid (HCl).

You can find the SDS sheets for all our reagents at

I accidentally added way too much Potassium Metabisulfite (KMBS) to my must/wine sample due to a miscalculation on our part. When I perform the SO2 titration I have to use more than a full syringe (5mL) of the SO2 Titrant to get a reading. What can I do? What should I do?

When testing for Free SO2, if you follow the procedures in the normal way and you end up using 5mL + 2.6mL more from a second syringe then your calculation at the end would not need to change. You would simply multiply total volume by 20 as stated in the manual, which would be 7.6*20 = 152

If you know you have high SO2 values and you want to use less of your SO2 Titrant (to conserve your reagents) you can use 10mL of your wine, add 15mL of DI water and then follow the remaining steps as usual, adding your Reactant and Acid solutions and titrating with the SO2 Titrant. This procedure would change the formula you use to calculate your ppm of SO2. Using the large formula for calculating Free SO2 content, listed in the manual (currently on page 6 of the SC-100A manual) your value for ‘S’ would change to 10mL of your wine sample (where normally this is 25mL). And then you can proceed with the calculation of the equation. You will not be able to simply use the 20*V calculation.

Here is the full equation:                                    ppm SO2 = (64*V*N*1000)/2*S  (listed in the manual)

For example: If you use a 10mL wine sample (S), perform the test and you use 3.5 mL of your SO2 Titrant (V), the equation would look like this:

ppm SO2 = (64*3.5*0.0156*1000)/2*10              =             174.72 ppm Free SO2

*When adding DI water to your wine sample, do not worry. This will not affect your SO2 values. Adding this water allows you to bring up your sample volume to a more manageable volume but will not affect your SO2 readings.

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.

When I run the MLF Assay, on average, how much of the wine sample should be left after heating it in the microwave?

After heating your wine sample for 90 seconds, as instructed in the manual, your sample should have approximately 7 to 8 ml of wine remaining.

Be sure and let it cool completely before bringing the volume back up to 10 mL!

Is it possible to use the Vinmetrica SC-50 for analyzing MALIC ACID levels on grapes (pre-harvest grape sampling), besides using it later for MLF assessment?


YAN Questions

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?

We always recommend checking your local regulations as they vary depending on where you are.

The small amount of formaldehyde in a YAN 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.

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.

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

Additional Information

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

Replacement SO2 Electrode Purchasing Guide

pH: how to measure it, what it is, and how to use it

Managing pH and TA

Reagent Tests

The KHP test: Verifying TA Titrant Accuracy

The Ascorbic Acid test: Verifying SO2 Reagents Accuracy

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

24 thoughts on “Frequently Asked Questions

  1. Hello,
    I’m a first time user of your wine testing services and I have already received your supply pack. I will be requesting 3 of the same test for 3 different vintages that I have. Do I order those 3 tests at your website first, then send in my 3 separate samples? Will your test lab know that I’ve paid for the 3 tests and will apply those purchased tests to each sample received?

    I just want to make sure I understand your process.

    Please let me know.



    1. Scott,
      Thank you for the inquiry. Our apologies for the delayed response, we were closed for the holidays. For future reference, you can do this either way. You can order the tests online ahead of time or you can send in your samples and we will bill you when the work is complete. As long as you fill out the labels that were provided with your lab services starter pack completely, we can usually link your name to your order. Otherwise we will reach out to you for payment.

      We have your samples now and are running the analysis. You should hear from us later on today with your results.


  2. I purchased the SC300 Pro kit, and can not tighten the plastic burette holder onto the stand. I am assuming that I slide the holder over the stand and turn the screw cap to tighten, but it doesn’t close tight enough. Am I missing something?


    1. Susan,
      We are sorry to hear you are having issues with your SC-300 Pro Kit. It might be best if you can send us some pictures so we can see what is going on. I can email you separately so that you have my contact information.

  3. Hi, I am using the SC100 for about the last 2 years to test for free SO2. After I add the 2 reagents to the 25ml’s of wine I power up the meter and if it reads zero I know I will not get a reading after titration. The meter seems to need to have numbers when I turn the meter on, then I power off and then back on to get a zero then it will read a titration. Is this the norm? I have recently also needed to also take the wire connectors out of the meter and then move the wires around to find the right spot in order for a reading, if I don’t it reads zero but then I start the titration and use all of the titrate and do not get a reading. I know that monthly 10ppm of SO2 is about 4 grams for a barrel so I use that as a guide so I think when I finally get a reading and the wine has used up close to the 10 ppm SO2, we are in the ball park. Any ideas with the connections and readings? I think there is a poor connection but not sure how to fix other than replace or move around. Once it seems to read ok I have been able to get the other 5 barrels analyzed. But I usually have to mess around for a half hour or so to get it to go? Please advise and thanks.

    1. Robert,
      It sounds like there could be a bad connection somewhere. Is this a new issue you are seeing or one that has been happening for a while? Have you looked at our Troubleshooting Guide under our Support tab? It can walk you through several steps to help determine what might be happening. If you think it is simply a wire/connection issue it will probably need to come in for repair and diagnostics. If the Troubleshooting Guide doesn’t help, please give our Tech Support line a call (760-494-0597) and we can give you some additional advice or give you an RMA number to send the unit and electrode in.
      Thank you for reaching out to us. We will work to get this resolved quickly for you.

  4. While measuring free so2, after adding acid reagent and reactant to my 25 ml sample, my reading started at 50 add then dropped to 0. I only added 2 cc and it stayed above 100. What should I do next?

    1. Mark,
      Thank you for reaching out to us. The initial reading of 50 that then drops down to 0 is okay. It can happen sometimes and does not indicate that anything is wrong.

      Just to confirm, you added 2mL of your SO2 Titrant during the titration of your sample? Or two drops of SO2 Titrant? If you only added two drops of your SO2 Titrant, this indicates that you have little to no SO2 in your wine sample. If you reached the endpoint after adding 2mL of the SO2 Titrant then you would take that value, 2 and multiply it by 20 to get your ppm SO2 in your wine sample.

      Make sure that you are constantly swirling your wine sample after adding the Acid and Reactant and during the time you are titrating the SO2 Titrant. Add the SO2 Titrant dropwise until you reach your endpoint. We have a quick how to video on our website or you can visit the Troubleshooting Guide which walks you through many SO2 testing scenarios.

      Let us know if you have additional questions or need more help. Your can also call our tech support line.

  5. How do I apply my Texas tax exempt certificate to eliminate sales tax from my order?

    1. Gary,
      Thank you for the inquiry. If you are NOT located in California, after you input your shipping address and select your state, the sales tax will disappear.

  6. I have ran the ABV test 3 times now and never get to the olive green color. ?? My samples after 24 or even 12 hours all have a blue tint before the test starts.???

    1. Hi, you are probably pipetting the wine sample incorrectly, adding too much. Read over the instructions in the manual for details on using the micropipettor to deliver 100 microliters precisely. Call my direct office line 760-494-0597 x 102 and we can walk through it.

  7. Hi, have had my SC-300 for several years, it’s great. Will you be offering a test for volatile acidity for the SC-300?

    1. Ken,
      We are glad to hear your SC-300 is working great for you. At this time we have no plans to offer an in-home VA test kit. The chemicals are quite noxious. We do offer VA testing through our Lab Services though.
      Thanks for the inquiry.

  8. Hi, couples questions here. Interested to use the S02 test on bottled cocktails and other also carbonated beverages. Will it be possible to take readings of bottled cocktails(spirit + citrus + sugar + water) and/or other carbonated beverages(sparkling wine/sparkling cocktails/etc.?)

    1. Jonathan,
      Thank you for contacting us. Yes, our SO2 analyzer can be used to test carbonated beverages. However, since you mentioned that there is citrus in these drinks you may have some issues depending on how much ascorbic acid is in your cocktail. If your ascorbic acid levels are significant then you can run in to some issues. If you suspect your ascorbic acid levels are low, we can provide you with a quick procedure to adjust for this. I think it may be best if you contact our Technical Support, either or 760-494-0597, and we can go over the specific requirements for your sample.
      Thank you

  9. I have the SC-100 instrument, which reaches the stop condition but then gives a reading that jumps around, even showing 0.00 in the process. I have yet to run the tests suggested – “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.”
    What is likely the problem and how should I attempt to remedy it?
    Thanks, Jim Benn

    1. Jim,
      You may want to try cleaning your electrode by soaking it in your acid solution for about 30 minutes then gently scraping at those two platinum wires to remove any deposits. It is possible your electrode could be dirty. After cleaning, I suggest you try the “Reagent Test” for the SO2 function. The instructions for this test can be found on the Troubleshooting Guide. If you hover over the Support tab, the Troubleshooting Guide should be listed at the top. Give the reagent test a try and let us know how it goes. There are also some other tests there you can try that will help us determine what might be going wrong with your instrument, if anything.
      Let us know if you have any questions.

  10. Hi,
    I am a homebrewer looking into the SC-200 for testing pH and TA of my sour beers during the brewing process. I see that the SC-200 is labeled as a Wine Analyzer Kit, and refers to Tartaric Acid in subsequent text. Will it be able to test pH and TA of beer given the expected byproduct of lactic acid?

    1. yes you can do pH and TA on beer with the SC200. The pH is independent of the beverage or whatever solution it’s measuring. The TA is also; it’s just a matter of how you calculate the final answer. Wine TA is usually reported as tartaric acid but the titration actually measures acidity as equivalents per liter (eq/L). If you assume the acid is mostly tartaric (true for wine) then you use the conversion factor for tartaric acid (75), as we do in our kit. For a sour beer you would use the factor for lactic acid (90). So you could just convert as:
      g/L lactic = 90/75 * g/L tartaric.

  11. I have SC-300 that will not go to CAL mode. CAL flashes briefly and that’s it. The unit cycle through like it in testing mode and I don’t believe it’s calibrating

    1. Alonzo,
      I think it would be best if you contacted our Tech Support line, 760-494-0597. Its probably best if we walk through the diagnostics over the phone.

  12. Question on using transfer pipettes to obtain the 25mL sample for titration. I understand that the pipettes come in a sealed sterile package. Are these pipettes intended to be used only once – or can they be sterilized and reused? If so – what is the recommended process for cleaning and/or sterilization? I usually sanitize anything that comes into contact with the wine with Starsan. If I clean the transfer pipette with Starsan and then use it to obtain a wine sample for titration – will it impact the SO2 (or other) results? Thanks!

    1. Jeff,
      Great question! These pipettes are to be used multiple times. No need to purchase tons of them. We recommend the following procedure. When getting ready to take your 25mL sample for testing, rinse the pipette with DI water then use a 70% ethanol spray to clean the pipette. (remember not to use a sulfite solution here because that will throw off your sulfite readings!) Spray the pipette and wipe down with a clean paper towel. Take your sample and perform your SO2 test. Before you move on to the next sample, spray the pipette again with ethanol and wipe down. Some customers also rinse the inside with DI water again before spraying the ethanol but that is not necessary. I am unfamiliar with Starsan but if it is a common “food safe” sterilant (that does not contain sulfite) it should be okay.
      Let us know if you have any other questions.

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