Indirect ultraviolet determination of cyanide by flow injection analysis using absorption of the Hg-EDTA complex at 250 nm

Abstract

The flow injection principle was used in the determination of cyanide ion by the decrease in the ultraviolet absorption of the Hg-EDTA complex at 250 nm. The decrease in the absorbance is linear with cyanide concentration in the range of 0.5–52 ppm. A manifold consisting of two lines was used. The EDTA carrier and the Hg-EDTA reagent streams were buffered at pH 10 (ammoniacal buffer). The method has a detection limit of 0.5 ppm cyanide. At a sampling rate of ca.60 samples per hour with 100-μl sample injections, precision was about 1% relative standard deviation. The effects of the concentration of the Hg-EDTA reagent, pH, sample volume, flow rate, coil length, and anion interference on the FIA-ultraviolet signals are reported.