Method Comparison and Evaluation for the Analysis of Weak Acid-Dissociable Cyanide

This study compared and evaluated three methods to determine weak acid-dissociable cyanide. An emphasis was placed on data quality using a performance-based ap proach to overcome the problems associated with cyanide analyses. The three methods compared were Standard Methods, 18th ed., Method 4500 CN- I (macro distillation, colorimetric finish); Bayer Method SA-61A (steam distil lation at pH 4.5, ion selective electrode finish); and Bayer Method SA-100 (FIA or flow injection analysis, gas diffusion separation, and amperometric detection). The study demonstrated method detection limits, recoveries of cyanide species, and use of ligand exchange reagents to improve selected cyanide species recoveries. Potential interfer ences were examined with the FIA procedure to demonstrate that the method would be applicable to industrial wastewater samples subject to NPDES regulations. This performance-based approach led to a successful means to measure weak acid-dissociable cyanide in an industrial effluent where other ...