Method 376.1

Sulfide (Titrimetric, Iodine)

This method is for the determination of total and dissolved sulfides in drinking, surface and saline waters, domestic and industrial wastes. Excess iodine is added to an aliquot of the sample which may or may not have been treated with zinc acetate to produce zinc sulfide. The iodine oxidizes the sulfide to sulfur under acidic conditions. The excess iodine is back titrated with sodium thiosulfate or phenylarsine oxide.

Acid insoluble sulfides are not measured with this test.  

The range of this mehod is sulfide in concentrations above 1 mg/L. 

Sulfur compounds such as sulfite, thiosulfate, and hydrosulfite which decompose in acid may yield erractic results.  Volatile iodine-comsuming substances can produce high results.  Aeration can result in loss of sulfide due to volatilization or reaction with oxygen.  Collect samples using a minimum of aeration.

(EPA: Office of Water)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   7 days from sample collection to analysis.
Preservatives:   Preserve samples with 2 mL of zinc acetate and raise pH to >9 with sodium hydroxide.
Required Preps:   500 mL HDPE or amber glass bottle
Collection Method:   Grab sampling
Analytical Methodology:   Titration
Documentation:   376.1

Analyte List*

Analyte Formula CAS Number Detection Limit

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.