Method SM 4500-CN-I

Weak Acid Dissociable (WAD) Cyanide

This method is for the determination of weak acid dissociable (WAD) cyanide in drinking and surface waters, domestic and industrial wastes.  It can also be used for sediment and solids matrix extracts. The working range for this method is 0.010 to 0.300 mg/L cyanide. 

Hydrogen cyanide (HCN), is liberated from a slightly acidified (pH 4.5 to 6.0) sample via distillation. The method does not recover cyanide from tight complexes that would not be amenable to oxidation by chlorine. The acetate buffer used in the distillation step contains zinc salts to precipitate iron cyanide as a further assurance of the selectivity of the method.

The method is similar to SM 4500-CN-C and US-EPA 335.4.



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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   14 days from collection to analysis. Analyze as soon as possible after collection.
Preservatives:   Preserve to pH < 12 with sodium hydroxide. Store at 4°C.
Required Preps:   250mL poly or glass bottle.
Collection Method:   Grab sampling.
Analytical Methodology:   Spectrophotometric

Analyte List*

Analyte Formula CAS Number Detection Limit
Weak acid dissociable cyanide

* 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.