Kinetic determination of mercury(II) at trace level from its catalytic effect on ligand substitution reaction between hexacyanoferrate(II) and nitroso-R-salt

Abstract

A kinetic method is described for the determination of mercury(II), based on its catalytic effect on the ligand substitution reaction between hexacynoferrate(II) and Nitroso-R-Salt. The reaction is followed spectrophotometrically by measuring the absorbance at fixed times at 720 nm, the λ_max of green coloured complex, [Fe(CN)₅NRS]^3– formed during the course of reaction under optimum reaction conditions <i style="">viz</i>, temp = 25.0±0.1 °C, pH = 6.5±0.02 and <i style="">I</i> = 0.1 M(KNO₃). The method is simple, sensitive, selective, rapid and allows the determination of as little as 10^–6 M of mercury with good accuracy and precision. The detection limit is computed by standard procedure and found to be 1.6 <img src='/image/spc_char/cross.gif' border=0> 10^–7M of [Hg²⁺]. The effects of few interfering and non-interfering cations and anions on mercury(II) determination have also been reported with relative standard deviations.