DETERMINATION OF CADMIUM IN BIOLOGICAL-MATERIALS BY FLAME ATOMIC-ABSORPTION SPECTROMETRY WITH FLOW-INJECTION ONLINE SORPTION PRECONCENTRATION

A new on-line preconcentration flame atomic absorption spectrometry (F AAS) system for trace element determination was developed based on sor ption of soluble metal complexes on the walls of a PTFE knotted reacto r using flow injection techniques. The system was applied to the deter mination of cadmium in biological materials. Cadmium complexed with so dium diethyldithiocarbamate was sorbed on the inner walls of the react or and eluted on-line by isobutyl methyl ketone. The retention efficie ncy was 81% at a sampling loading rate of 5.2 ml/min. The enhancement factor was 66 and the concentration efficiency was 61/min with a 50 se c preconcentration period, consuming 4.2 ml sample. A detection limit of 0.1 mu g/l. Cd (3 sigma) was obtained with a sampling frequency of 55/hr. The precisions were 1.2% RSD for 20 mu g/l. Cd (N = 11). Thiour ea and ascorbic acid/phenanthroline were used to overcome interference s from copper and iron, respectively. The analytical results obtained for powdered rice and human hair standard reference materials were in good agreement with the certified values.