Determination of copper, manganese and nickel in biological samples and sea-water by flow injection on-line sorption preconcentration in a knotted reactor coupled with electrothermal atomic absorption spectrometry
A flow injection system with on-line sorption preconcentration of copper, nickel and manganese with ammonium pyrrolidinedithiocarbamate (APDC) or 8-hydroxyquinoline (HQ) in a knotted reactor (KR) coupled with electrothermal atomic absorption spectrometry was developed. APDC offered better performance characteristics than HQ for the preconcentration of copper and nickel but could not be employed for manganese. The performance characteristics of the determination of copper and nickel with APDC were: detection limits (3σ), 6.0 and 7.6 ng l–1, precision (RSD) 2.5% for 0.2 µg l–1 and 1.5% for 0.2 µg l–1 and enhancement factors 44 and 21 using a 30 s preconcentration time. The corresponding parameters for the determination of manganese with HQ were detection limit 29.0 ng l–1, precision (RSD) 2.9% for 0.4 µg–1 manganese and enhancement factor 8 with a 30 s preconcentration time. The sampling frequency was 26 h–1. The accuracy of the method was demonstrated by the analysis of certified reference materials and by recovery measurements on spiked samples.