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R9 Laboratory SOP 565
SULFIDE BY TITRATION
Summary
This method is applicable to the measurement of total sulfides in drinking, surface and saline waters, domestic and industrial waste. This SOP is based on EPA Method 376.1, issued 1978. Acid insoluble sulfides are not measured by the use of this test. The method quantitation limit is 1 mg/L sulfide.
Excess iodine is added to a sample that has been preserved with zinc acetate to precipitate zinc sulfide. The iodine oxidizes the sulfide to sulfur under acidic conditions. The excess iodine is backtitrated with sodium thiosulfate.