Determination of trace amounts of mercury(II) and silver(I): a catalytic method

A catalytic method has been developed for the determination of trace amounts of mercury(II) and silver(I) based on their catalytic effect on the rate of a ligand substitution reaction. The reaction studied involved the substitution of cyanide in hexacyanoferrate(II) by isonicotinoyl hydrazide and the reaction was monitored spectrophotometrically. Satisfactory results were obtained for the determination of mercury(II) in the range 0.12–0.48 µg ml–1 and silver(I) in the range 0.03–0.15 µg ml–1. The relative standard deviation for mercury(II) was 0.743% and for silver(I) 0.696%. The effect of foreign ions on the determination was studied.