STOPPED-FLOW INJECTION KINETIC DETERMINATION OF MULTICOMPONENT SAMPLES - SIMULTANEOUS DETERMINATION OF MERCURY(II) AND SILVER(I)

A catalytic method is proposed for the simultaneous determination of m ercury(II) and silver(I) based on their catalytic effect on the ligand substitution reaction rate between hexacyanoferrate(II), [Fe(CN)(6)]( 4-) and alpha,alpha'-bipyridyl. The reaction was monitored with a stop ped-flow injection method and detected spectrophotometrically at 536 n m. Most of the commonly coexisting foreign ions do not interfere with the determination, except for Fe3+, Co2+ and Zn2+. The calibration gra phs are linear in the ranges 0-75 ng ml(-1) Hg(II) and 0-64 ng ml(-1) Ag(I), and the detection limits are 0.5 ng ml(-1) Hg(II) and 1.0 ng ml (-1) Ag(I), respectively. Mercury(II) and silver(I) content in tap wat er, wastewater and a synthetic sample has been determined with the pro posed procedure, the relative standard deviations being 3.52-5.20% for mercury (II) and 3.20-4.39% for silver(I).