IMMOBILIZED CYSTEINE AS A REAGENT FOR PRECONCENTRATION OF TRACE-METALS PRIOR TO DETERMINATION BY ATOMIC-ABSORPTION SPECTROMETRY

A flow injection system combining on-line preconcentration using immobilized cysteine with atomic spectrometric detection was developed for the determination of trace metals. The chelating reagent, cysteine, was immobilized on controlled pore glass. The amino group of cysteine was used to covalently bind it to silanized controlled pore glass through the bifunctional reagent glutaraldehyde. The immobilized reagent was then packed into a mini-column and used for the preconcentration of trace metals in a flow system with atomic absorption spectrometric detection. The immobilized reagent was used to preconcentrate copper, zinc, cadmium, lead, cobalt and mercury in aqueous acidic media with capacities of 7.86, 7.88,12.48,11.66,5.50 and 6.06 mmol g-1 of the dry resin, respectively. The pH dependence of the extraction of the metal ions by the resin, the type of eluent utilized, the column length and flow rate were evaluated. The effect of interference from other metal ions was investigated. The sampling frequency was 20 h-1.