Abstract

Tohru Nagahiro and Katsuya Uesugi

A method has been established for the determination of trace amounts of zinc employing preconcentration of zinc with 4-(2-pyridylazo) resorcinol(PAR) and the adsorbent (trioctylmethylammonium/bromate ion-pair material supported on biphenyl). Zinc reacts with PAR to form a zinc/PAR complex anion. The zinc/PAR complex forms a ternary complex with triocrylmethylammonium cation in a column and then the ternary complex is adsorbed onto microcrystalline biphenyl. The column content is dissolved with dimethylformamide and zinc is determined using atomic absorption spectrometry. The optimum pH range for the formation of zinc/PAR complex and its adsorption onto adsorbent was 8.1 -10.9. The flow - rate did not affect the adsorption in the range of 0.5 to 8.0 ml min -1 and the adsorption remained maxium and constant up to 500ml of aqueous phase. The calibration graph was linear up to 5 u g of zinc in 5ml of dimethylformamide solution. Seven replicate analyses of a sample solution containing 2.0 M g of zinc gave a relative standard deviation of 1.1%. The proposed method has been successfully applied to the determination of zinc in aluminium alloy, human hair and mussel samples.

zinc determinaton; atomic absorption spectrometry; 4-(2-pyridylazo)resorcinol; trioctylmethylamonium/bromate/biphenyl adsorbent.

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