1.1 This test method is used for the determination of total cyanide in solid waste and soil samples after a preliminary alkaline extraction. Simple cyanide (CN-) salts of Group 1 and Group 2 (alkali and alkaline earth) metals; soluble alkali and alkaline earth salts of zinc, copper, cadmium, mercury, nickel, silver, and iron cyanide complexes; and insoluble metal-metal cyanide complexes, such as Prussian Blue, are quantitatively recovered. Gold, platinum group metals, and cobalt cyanide complexes are not recovered. 1.2 Cyanide complexes are extracted into an alkaline solution. The filtered alkaline extract is injected into an acidic stream and passed through ultraviolet radiation at 312nm. The UV irradiation dissociates metal cyanide complexes to form hydrogen cyanide (HCN). The HCN diffuses through a semi porous hydrophobic membrane into a dilute sodium hydroxide solution and converts back to the cyanide ion (CN-). The cyanide ion passes across a silver electrode oxidizing the silver and generating electrons. The electrons generated produce a signal that is proportional to the cyanide concentration in the extract. The original cyanide content in the soil or waste is then calculated. 1.3 Analysis with ligand injection and the ultraviolet (UV) irradiation source turned off determines the weak and dissociable (WAD) and available cyanide concentration in the extract. Free cyanide cannot be determined because of the change of equilibrium conditions during the extraction process. 1.4 This test method detection limit (MDL) is ~0.2 mg/Kg and the minimum level (ML) is ~0.5 mg/Kg (actual MDL and ML to be determined by interlaboratory study data). The applicable range of this test method is 0.5 to 100 mg/Kg using a 200 uL sample loop. Extend the range to higher concentrations by dilution or using a smaller sample injection volume. 1.5 This test method can be used by experienced analysts experienced with equipment using segmented flow analysis (SFA) and flow injection analysis (FIA) or working under the close supervision of such qualified persons. 1.6 Units--The values stated in SI units are to be regarded as the standard. No other units of measure are included in this standard. 1.7 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 and health practices and determine applicability or regulatory limitations prior to use. Specific hazard statements are given in Section 9.
Current cyanide methods for total cyanide in solid waste rely on a preliminary acid distillation followed by titration or colorimetric tests. Acid distillations do not quantitatively recover the strong metal metal cyanide complexes. The U.S. EPA has ruled that strong metal metal cyanide complexes are included in the definition of total cyanide; therefore, the results based on preliminary acid distillation are biased low. This test method will rapidly and quantitatively extract all inorganic cyanide complexes including those not quantitatively recovered by distillation. This test method then allows measurement of cyanide by any ASTM test method. Elimination of distillation shortens analysis times allowing more samples to be tested per day and lowering the cost of analysis.
Keywordstotal cyanide; available cyanide; free cyanide; Berlin Blue; FFC; solid waste; RCRA; weak and dissociable cyanide; strong metal cyanide complexes; insoluble cyanide; colloidal cyan
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
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