Inverse photometric detector, based on Eriochrome Black T, for trace metal determination by high-performance liquid chromatography

Abstract

A simple post-column reactor based on Eriochrome Black T (EBT) has been developed to determine trace metals after separation on a silica-based cation-exchange column. Quantitative detection is performed by measuring the decrease in the absorbance of the post-column reactant. Quantitative analysis of nine metals in 16 min can be achieved. Linear calibrations up to 10 p.p.m. for cadmium, cobalt, copper, indium, iron(III), iron(II), magnesium, manganese, nickel and zinc are possible with limits of detection of 2–5 ng. The relationship of the cation ion-exchange chromatography and the organic acid eluent to the post-column reactor is discussed. The system was used to determine cobalt, copper, iron, manganese and nickel in standard alloys and the accuracy of the method is shown to be very good with coefficients of variation in the range 1–11%.