Electrothermal atomic absorption spectrometric determination of cadmium and lead in environmental, botanic and biological samples by different permanent modifiers

Permanent modifiers (Zr, W, Ru, Zr-Ru and Zr-W) thermally deposited on platforms inserted in pyrolytic graphite tubes and Pd + Mg(NO3)(2) conventional modifier mixture have been employed for the determination of cadmium and lead in dissolved environmental, botanic and biological samples by electrothermal atomic absorption spectrometry (ETAAS). Optimum masses and mass ratios of permanent modifiers for Cd and Pb have been investigated. 240 mug Zr + 240 mug W or 240 mug Zr + 200 mug Ru has been found as efficient as 5 mug Pd + 3 mug Mg(NO3)(2) for obtaining thermal stabilization and for avoiding most serious interferences. Comparison has been made in terms of pyrolysis and atomization temperatures, atomization and background signal shapes, characteristic masses and detection limits. Long-term stability curves for analytes in samples with Zr, Zr-Ru, Zr-W and Pd + Mg(NO3)(2) have been obtained. Cadmium and lead contents determined in certified and standard reference materials by using optimum conditions studied were in agreement with the certified reference materials.