A novel approach to quantifying elemental sulfur (S 0 ) in environmental samples

Abstract

The quantification of elemental sulfur (S 0 ) is an important part of monitoring and controlling sulfur-involving processes. Existing methods of S 0 detection either require significant time or involve the use of toxic chemicals. We have developed and validated a new method to determine S 0 in environmental samples using calorimeter-ion chromatography (IC), in which S 0 is fully oxidized to sulfur trioxide (SO 3 ) with pure oxygen at 20 atm in a calorimeter. The resulting SO 3 is then absorbed by a sodium bicarbonate (NaHCO 3 ) solution and analyzed using IC. To verify this method, standard samples with various sulfur contents (5–200 mg S), possible interfering substances (SO 42 , SO 32 , S 2 O 32 and S 2 ), and mixed environmental samples were tested and compared. The high correlation of R 2 ¼ 0.999 between the examined and theoretical values was obtained with a high recovery rate of 95% and a low relative standard deviation (RSD) of 1%. Samples containing at least 25 mg of S 0 were accurately measured (recovery error < 5%). Thiosulfate was identified as the main interfering substance, and pretreatment was needed to eliminate it. This new method is more efficient, cost-effective, easier to operate, and more secure and accurate than existing methods.