Validation of a Simpler Method for Determination of Atmospheric Sulfur Dioxide

The determination of atmospheric sulfur dioxide as aqueous bisulfite using 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) was validated as a simple, rapid and reliable procedure. Standard sulfur dioxide concentrations in air (0-2.6 ppm) were generated by means of a permeation device. Sulfur dioxide from air samples was absorbed in pH 7 phosphate buffer and determined as bisulfite. The mean percentage recovery of sulfur dioxide is 101.4; the slope of the validation line determined by linear regression analysis (calculated vs. found) is 1.014 ppm found/calculated (1.4% absolute error; 0.9976 correlation coefficient).