Tag: sulfite in wine

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Not Getting An SO2 Reading.. Why?

We get this question a lot so we thought we would discuss it here.  [Note: Most of this information is available on our troubleshooting guide under SO2 Problems]

There’s two situations that may cause concern about the reading.

  1. Your instrument indicates an endpoint (beeps) right away, either before adding any SO2 Titrant, or after adding just 1 or 2 drops.
  2. Your instrument apparently never indicates an endpoint, even after titration with a large amount of the SO2 Titrant.

Situation (1.) happens a lot. Most of the time, this is just the normal endpoint response, telling you that your wine’s ppm of free SO2 is zero. To verify that the endpoint indication is valid, add 1 drop of 10% KMBS and stir.  The signal should drop to below 50 right away, and the endpoint indicators should stop signaling.  If the endpoint signaling does not stop, you may have a problem with the instrument.

Situation (2.) also crops up from time to time. Let’s say you are running an SO2 test on your wine and you use the ENTIRE 5mL syringe of SO2 Titrant, but your instrument stays on 0.00 or a low number, indicating that you still haven’t reached the endpoint. This would normally mean you have over 100 ppm free SO2 in your wine. But you’re pretty sure there isn’t that much SO2 present. So your instrument must not be working, right?

Actually, it might be working just fine! Keep Reading More!

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How does Vinmetrica and the Ripper titration stack up for SO2 measurements?

By: Rich Sportsman, President (March 27, 2020)

There are several reports comparing various methods for determining free and total sulfites (SO2). Aeration oxidation (AO) and Ripper titration methods (like Vinmetrica, Hanna, and old starch color change techniques) are the most commonly employed. In addition there are a number of methods based on spectrophotometric techniques or color reactions that have come into use in recent years. Here I want to focus on the performance of the AO and Ripper methods vs. others, and vs. each other.

We have generated lots of our own data comparing AO and Vinmetrica’s SO2 test, and we know without any doubt that, with the exception of exotic samples (like wines made from ascorbic acid-containing fruit, see this BLOG HERE), the Vinmetrica system produces results that are indistinguishable from those of the AO method. But I think it’s time to revisit the information that’s out there on others’ assessment of the comparison of these techniques. Keep Reading More!