Spectrophotometric determination of mercury in environmental sample and fungicides based on its complex with o-carboxy phenyl diazoamino p-azobenzene

In the present method a new reagent o-carboxyphenyl diazoamino p-azobenzene has been synthesised for the determination of mercury spectrophotometrically. The method is based on the reaction of mercury with the reagent in alkaline medium where the reagent is in the aci-form. The purple violet coloured dye–mercury complex showed an absorption maxima at 540 nm. Beerʹs law is valid over the concentration range of mercury from 0.08 to 0.8 μg ml−1 (0.08–0.8 ppm). The molar absorptivity and Sandellʹs sensitivity were found to be 2.22×105 mol−1 cm−1 and 0.0009 μg cm−2, respectively. The method has been successfully applied to the determination of mercury in air, water, soil and fungicide samples.