UOP 827-81

A Control and a Precision method are used for the determination of apparent hydrogen sulfide in amine solutions. Hydrogen sulfide is determined by oxidation with standard iodine solution in an acid medium. Thiosulfate, if present, is also titrated and is included as apparent H2S in the calculation. Thiosulfate may be determined by using UOP Method 818, and the value thus obtained subtracted from the apparent H2S concentration. The lower limit of detection is approximately 25 grains/gallon.