ASTM D7284-20

1.1 This test method is used to determine the concentration of total cyanide in an aqueous wastewater or effluent. This test method detects the cyanides that are free (HCN and CN^-) and strong-metal-cyanide complexes that dissociate and release free cyanide when refluxed under strongly acidic conditions.

1.2 This test method may not be applicable to process solutions from precious metals mining operations.

1.3 This procedure is applicable over a range of approximately 2 to 500 μg/L (parts per billion) total cyanide. Higher concentrations can be measured with sample dilution or lower injection volume.

1.4 The determinative step of this test method utilizes flow injection with amperometric detection based on Test Method D6888. Prior to analysis, samples must be distilled with a micro-distillation apparatus described in this test method or with a suitable cyanide distillation apparatus specified in Test Methods D2036.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in 8.6 and Section 9.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.