EPA-NERL: 335.3: Cyanide by Automated Colorimetry
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Official Method Name
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Cyanide, Total (Colorimetric, Automated UV) |
|---|---|
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Current Revision
| Issued 1978 |
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Media
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WATER |
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Instrumentation
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Automated Spectrophotometer |
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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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Cyanide, as HCN, is released from cyanide complexes by means of UV digestion and distillation. Cyanides are converted to cyanogen chloride by reactions with chloramine-T which subsequently reacts with pyridine and barbituric acid to give a red-colored complex that is measured with an on-line colorimeter. |
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Scope and Application
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The automated method determines cyanide in drinking and surface waters; domestic and industrial wastes. |
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Applicable Concentration Range
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0.005 - 0.5 mg/L |
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Interferences
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(A) Thiocyanates: Thiocyanates are positive interferences. (B) Sulfides: Sulfides can adversely effect the color procedure. Remove sulfide by precipitating with cadmium carbonate, and remove precipitate by filtration. |
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Quality Control Requirements
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None. |
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Sample Handling
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Samples are collected in plastic bottles, and preserved with sodium hydroxide. If chlorine is present (test for chlorine using KI starch paper or superior method), add sufficient ascorbic acid to remove it. Samples are then refrigerated. |
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Maximum Holding Time
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14 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. |
