Spectrophotometric study of the reaction of zinc with O-hydroxybenzenediazoaminoazobenzene and its application.

A highly sensitive and selective procedure for spectrophotometric determination of zinc has been developed. At pH 10.6, in the presence of emulsifier p-octylpolyethyleneglycol phenylether (OP), zinc forms an orange-red complex with o-hydroxybenzenediazoaminoazobenzene (HDAA) which has an absorption maximum at 525 nm. The molar absorptivity is 1.50 x 10(5) 1.mole(-1).cm(-1). Beer's law is obeyed for zinc in the range 0-13 mug/25 ml. The method has been applied to the spectrophotometric determination of trace amounts of zinc in aluminium alloy and in human hair. The proposed method is simple, rapid and accurate. No heating or separation is required.