USGS-NWQL: I-3300: Cyanide in Water by Colorimetry
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Official Method Name
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Total Cyanide in Water by Colorimetry with Pyridine-Pyrazolone |
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Current Revision
| 1985 |
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Media
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WATER |
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Instrumentation
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Spectroscopy (Colorimetry; Photometry) |
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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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Methods for the Determination of Inorganic Substances in Water and Fluvial Sediments, Techniques of Water-Resources Investigations of the United States Geological Survey, Book 5, Chapter A1 Edited by Marvin J. Fishman and Linda C. Friedman |
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Brief Method Summary
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This method is based on the chlorination of cyanide and the subsequent reaction of the product with a mixed solution of pyridine-pyrazolone to form a stable complex dye. The method detects only simple cyanides; therefore, any complex cyanides present must be broken down. The decomposition of complex cyanides is accomplished by an acid reflux and distillation prior to the colorimetric procedure. The distillation also removes certain interferences from water samples. |
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Scope and Application
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The method covers the determination of cyanide in water and water-suspended sediment containing at least 0.01 mg/L of cyanide. The test method may be used to determine cyanide in bottom material containing at least 0.5 mg/kg. Total cyanide in water-suspended sediment may be determined if each sample is shaken vigorously and a suitable aliquot of well mixed sample withdrawn. |
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Applicable Concentration Range
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0.01 mg/L - * (* Method does not specify an upper detection limit.) |
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Interferences
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(1) Oxidizing agents can destroy cyanides during storage. (2) Sulfide can complex with cyanide in sample or distillate. (3) Fatty acids cause interference during distillation. (4) Carbonate causes interference during distillation. (5) Aldehydes cause interference during distillation. (6) Glucose/Sugars cause interference during distillation. (7) Sulfur-containing compound causes interference during distillation by forming free sulfide that is captured in distillate. |
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Quality Control Requirements
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Calibrate instrument using calibration standards (CAL); quality control samples (QCS); and laboratory blanks (LB) analyzed at a minimum of 1 for every 10 samples. |
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Sample Handling
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Container Description: 250 mL Polyethylene bottle. Treatment and Preservation: use unfiltered sample to rinse bottles; then add NaOH to pH>12 to collected sample, chill and maintain at 4 deg C; ship immediately. |
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Maximum Holding Time
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180 days |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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