Generic Preconcentration/Dilution Sequential Injection Manifold for the Automated Amperometric Determination of Free Cyanides from Sub-ppb to High ppm Levels

Abstract

Hydrogen cyanide and its simple sodium and potassium salts are among the most rapidly acting poisons affecting the central nervous system and a ­potentially terrorism threat. The present study reports a generic flow manifold based on sequential injection analysis coupled to gas diffusion that allows both preconcentration and dilution of real samples in a practically single-channeled configuration. By selection of the appropriate sequence and instrumental variables (volumes, flow rates etc.) cyanides can be determined from the sub-ppb (<1 μg L⁻¹ e.g. in tap water samples) to high ppm (>500 mg L⁻¹ e.g. in electroplating baths) levels at sampling rates between 3 and 22 h⁻¹.