DETERMINATION OF SE IN HUMAN SERUM BY AAS USING ELECTROTHERMAL ATOMIZATION WITH LONGITUDINAL ZEEMAN-EFFECT BACKGROUND CORRECTION OR FLOW-INJECTION HYDRIDE GENERATION

Two methods are described for the determination of selenium in human s erum by atomic absorption spectrometry (AAS) using either electrotherm al atomization (ET) with longitudinal Zeeman-effect background correct ion or flow injection (FI) hydride generation (HG). ETAAS allowed the direct determination of selenium in an appropriately diluted serum sam ple (1:10). Serum selenium was stabilized prior to atomization by a ma trix modifier containing 1500 mg/L Pd and 1000 mg/L Mg nitrate. Calibr ation was performed by the method of standard addition. FI-HGAAS requi red a nitric/perchloric acid digestion procedure prior to analysis. Ca libration was performed using a calibration curve in 1 mol/L hydrochlo ric acid. Both methods provided analytical data for a reference serum sample which was in close agreement with the certified value. Precisio n (range 2-5%) and sensitivity (similar to 50 pg) were comparable for both methods. However, ETAAS demonstrated a lower relative limit of de tection, 6.5 mu g/L, compared to FI-HGAAS with 11.8 mu g/L. Accurate d eterminations of low selenium levels in a small sample volume (100 mu L serum sample) was obtained with both methods.