ICP-OES Determination of cobalt in natural water using a flow injection system after preconcentration on activated carbon

Abstract

An on-line cobalt preconcentration system is described for the ICP-OES determination of cobalt in drinking water in a flow injection system. The methodology developed is simple and rapid. Trace amounts of cobalt were pre-concentrated by sorption on a conical mini column packed with activated carbon (AC) at pH 9.5, with retention of 95%. The cobalt was removed from the conical mini column with 20% (v/v) nitric acid. An enrichment factor of 95-fold for a sample volume of 50 mL was obtained. The detection limit for the preconcentration method proposed was found to be 20 ng L–1. The precision for 10 replicate determinations at the 5-µg L–1 Co level was 2.7% relative standard deviation, calculated from the peak heights obtained. The calibration graph preconcentration method for cobalt species was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 µg L–1. The method was successfully applied to the determination of cobalt in natural water samples.