DETERMINATION OF COPPER, MANGANESE AND NICKEL IN BIOLOGICAL SAMPLES AND SEA-WATER BY FLOW-INJECTION ONLINE SORPTION PRECONCENTRATION IN A KNOTTED REACTOR COUPLED WITH ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A flow injection system with on-line sorption preconcentration of copp er, nickel and manganese with ammonium pyrrolidinedithiocarbamate (APD C) or 8-hydroxyquinoline (HQ) in a knotted reactor (KR) coupled with e lectrothermal atomic absorption spectrometry was developed. APDC offer ed better performance characteristics than HQ for the preconcentration of copper and nickel but could not be employed for manganese. The per formance characteristics of the determination of copper and nickel wit h APDC were: detection limits (3 sigma), 6.0 and 7.6 ng l(-1), precisi on (RSD) 2.5% for 0.2 mu g l(-1) and 1.5% for 0.2 mu g l(-1) and enhan cement factors 44 and 21 using a 30 s preconcentration time. The corre sponding parameters for the determination of manganese dth HQ were det ection limit 29.0 ng l(-1), precision (RSD) 2.9% for 0.4 mu g(-1) mang anese and enhancement factor 8 with a 30 s preconcentration time. The sampling frequency was 26 h(-1). The accuracy of the method was demons trated by the analysis of certified reference materials and by recover y measurements on spiked samples.