Automated flow injection spectrophotometric determination of zinc using zincon: applications to analysis of waters, alloys and insulin formulations

Abstract

An automated flow injection method for the determination of zinc, based on the zincon method with differential demasking of the cyanide metal complexes with cyclohexanone, is described. Zinc concentrations, in the range 1–10 µg ml^–1 can be determined with a precision greater than 1%, at a rate of 80 determinations per hour and with a detection limit of 0.05 µg ml^–1. Because of the short reaction time (27 s), interferences arising from the breakdown of other metal cyanide complexes are considerably reduced. The method was evaluated for the determination of zinc in alloys and insulin formulations and the results obtained were in good agreement with those of reference methods. Recovery studies on spiked sample solutions gave excellent results.