SEDL / STP / STP886-EB / STP36363S

Comparison of Analytical Methods for the Determination of Total and Free Cyanide in Solid Waste

Barsotti, LR
Section head, Inorganic Analytical Section, and senior staff research chemist, Center for Technology, Kaiser Aluminum and Chemical Corp., Pleasanton, CA

Palmer, TA
Section head, Inorganic Analytical Section, and senior staff research chemist, Center for Technology, Kaiser Aluminum and Chemical Corp., Pleasanton, CA

Pages: 10    Published: Jan 1985

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Abstract

Historically, standard reflux distillation methods have been used to determine the total cyanide in aqueous systems. This paper compares such a method with an automated total cyanide method and demonstrates good recovery and precision by both methods. The automated method has the advantages of speed and convenience, as well as being less labor-intensive.

Free cyanide, identified as the sum of hydrocyanic acid and cyanide ion in aqueous solution, is determined by a microdiffusion and a modified Roberts-Jackson method. A comparison of results obtained by both methods showed free cyanide was only about 2% of the total cyanide in an aqueous sample. Total cyanide methods are useful for screening the cyanide content of samples, but free cyanide methods increase the information available and improve the understanding about the kinds of cyanide compounds in a sample. Even greater selectivity of analytical methods for cyanide compounds in waste is desirable and a challenge to analytical chemists.