RT Journal Article SR Electronic T1 Simplified Method for Free SO2 Measurement Using Gas Detection Tubes JF American Journal of Enology and Viticulture JO Am. J. Enol. Vitic. FD American Society for Enology and Viticulture SP ajev.2013.13003 DO 10.5344/ajev.2013.13003 A1 Zachary Pegram A1 Misha T. Kwasniewski A1 Gavin L. Sacks YR 2013 UL http://www.ajevonline.org/content/early/2013/05/30/ajev.2013.13003.abstract AB We describe a modification of the classic Monier-Williams method for free sulfur dioxide (SO2) measurement in wines using inexpensive SO2 detection tubes developed for the mining industry. In the modified method, an acidified wine sample is treated with an antacid tablet to evolve CO2in situ and the gas flow directed to a commercial SO2 detection tube. The length of tube that changes color is proportional to the original free SO2 concentration. Initial calibration of the tubes was performed in model wines using Aeration-Oxidation as a reference method. Using a 20 mL sample, the SO2 Tube method achieves a linear response from 5–40 mg/L. Accuracy was evaluated by measuring free SO2 concentrations in 16 wines (7 whites, 9 reds) by the SO2 Tube method in comparison to the A-O reference method. Free SO2 concentrations for individual wines measured by each method were within ±2 mg/mL, and the RMSE was 0.89 mg/L. The limit of detection of the SO2 Tube method was 3.3 mg/L in wine. The SO2 Tube method has several advantages over A-O, including requiring less time per analysis and no specialized glassware or equipment. The major consumable cost is the detection tubes, which can be conserved in exchange for precision by using smaller sample sizes.