This method is for the determination of inorganic cyanide in wastes or leachate. The method detects inorganic cyanides that are present as either soluble salts or complexes. Values for both total cyanide and cyanide amenable to chlorination are reported. The "reactive" cyanide content of a waste, that is, the cyanide content that could generate toxic fumes when exposed to mild acidic conditions, is not distilled by this method. However, this method may be used to quantify the concentration of cyanide from the reactivity test.
The cyanide, as hydrocyanic acid (HCN), is released from samples containing cyanide by a reflux-distillation operation under acidic conditions and absorbed in a scrubber containing a sodium hydroxide solution. The cyanide ion in the absorbing solution is determined by automated UV colorimetry. In the automated colorimetric measurement, the cyanide is converted to cyanogen chloride (CNCl) by reaction with Chloramine-T at a pH less than 8 without hydrolyzing to the cyanate. After the reaction is complete, color is formed on the addition of pyridine-barbituric acid reagent.
Chlorine and other oxidizing agents can decompose most cyanides.
NOTE: This method is an update of and replaces Method 9012A.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | 14 days from sample collection to prepartion if properly preserved. |
| Preservatives: | Samples should be cooled to 4°C. Add 50% NaOH until the pH is ≥ 12. |
| Required Preps: | 1L HDPE or amber glass bottle |
| Collection Method: | Grab sampling |
| Analytical Methodology: | UV Colorimetry |
| Documentation: | 
9012B
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Cyanides | CN- |
57-12-5 |
1 |
mg/L |
* 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.