Electrothermal atomic absorption spectrometric determination of cadmium and lead with stabilized phosphate deposited on permanently modified platforms

Abstract

Some drawbacks of the phosphate modifier such as reagent blank contribution and background absorption in electrothermal atomic absorption spectrometric determination of cadmium and lead are substantially alleviated by application of small amounts of phosphate, approximately 0.2 μmol (25 μg of NH 4H 2PO 4 or (NH 4) 2HPO 4), on the integrated platform of transversely heated graphite atomizer pre-treated with 2.7 μmol of Zr (250 μg) or W (500 μg) and 0.1 μmol of Ir (20 μg). Pyrolysis temperatures for Cd and Pb are up to 900 and 1100 °C for aqueous solutions and within 400–600 °C (Cd) and 750–850 °C (Pb) for biological fluids (urine, blood) and tissues (hair, liver, muscle) solubilized with tetraethylammonium hydroxide. The thermally stabilized phosphate on Zr–Ir or W–Ir treated platforms serves as a permanent modifier in analyses of environmental waters by multiple hot injections of large sample aliquots. Applications to water and biological certified reference materials are tabulated and show good agreement with certified values. Characteristic masses are 0.7–1.0 pg for Cd and 26–31 pg for Pb.