EPA-NERL: 376.1: Sulfide by Titrimetry
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Official Method Name
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Sulfide (Titrimetric, Iodine) |
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Current Revision
| Issued 1971; Editorial Revision 1978 |
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Media
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WATER |
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Instrumentation
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Titration |
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Method Subcategory
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Inorganic |
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Method Source
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Citation
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Brief Method Summary
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Excess iodine is added to a 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. |
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Scope and Application
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This method determines total and dissolved sulfides in drinking, surface and saline waters; domestic and industrial wastes. |
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Applicable Concentration Range
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Greater that 1 mg/L. |
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Interferences
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(A) Sulfur compounds: Sulfur compounds such as sulfite, thiosulfate, and hydrosulfite, which decompose in acid may yield erratic results. (B)Volatiles: Volatile iodine-consuming substances can produce high results. (C) Aeration: Aeration can result in loss of sulfide due to volatilization or reaction with oxygen. |
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Quality Control Requirements
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None. |
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Sample Handling
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To determine dissolved sulfides, or sulfides in an unpreserved sample, analyze immediately. MCAWW, Table 1 specifies to add 2 mL of zinc acetate and to raise the pH above 9. |
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Maximum Holding Time
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7 days (MCAWW, Table 1). |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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None. |
