Determination of zinc in pharmaceutical products by use of a sequential injection analysis system

A sequential injection analysis (SIA) system is proposed for the determinat ion of zinc in pharmaceutical samples. The method is based on the spectroph otometric detection of zinc using xylenol orange as a colour reagent at 568 nm. The system can be used to monitor zinc at a frequency of 30 samples h( -1) with an average recovery of +/- 98.5% and a relative standard deviation of less than 1%. A linear relationship between peak height and zinc concen tration is obtained between 10 and 60 mg L-1. The results obtained are in g ood agreement with those obtained by use of a standard method.