SO₂ concentrations are monitored throughout winemaking as it is the most common antimicrobial agent used in preventing spoilage. Accurate measurement is therefore important in the quality control of wines. The textbook concentration for antimicrobial effect is considered 0.8 mg/L of free SO₂ in the molecular form. Effective concentrations are heavily based on the pH of the wine. Higher pH values require greater concentrations of SO₂ to achieve the antimicrobial effect as less of the desired form is present. Over time SO₂ will also bind to many compounds in wine, so tests are run periodically to determine both the free and bound fractions. Target concentrations are based on amounts needed to achieve 0.8 mg/L according to the wine’s pH.

The two common methods used to test SO₂ are an aerated distillation that sweeps the volatile gas from the wine and traps it into a solution that can be analyzed through titration, and a color based titration using an iodine reagent known as the Ripper method. Free and total SO₂ are both tested the same way, except that the total measurement requires the addition of a strong chemical base (usually NaOH) to the wine sample in order to force the bound form to dissociate. Concentrations are usually reported as mg/L measurements.