Catalytic diazotization using silver and gold nanoparticles and spectrophotometric determination of parathion residues in fruit and soil

The catalytic activity of silver and gold nanoparticles in the spectrophotometric determination of parathion using 1-naphthol as a new coupling reagent to form an azo dye is described. It is based on the reduction of nitro group in parathion with zinc/HCl to form an amino derivative, which is diazotized and subsequently coupled with 1-naphthol to form an orange colored azo dye in alkaline medium. The size and shape effect of silver and gold nanoparticles in the time for diazotization is thus studied. The important analytical parameters and optimum reaction conditions have been evaluated.