Chemical modifiers in a tungsten coil electrothermal atomizer.

Abstract

A critical evaluation of the use of chemical modifiers [(NH₄)₂HPO₄, NH₄H₂PO₄ and Pd as Pd(NO₃)₂] for the determination of Pb in acid-digested blood and hair was performed in a non-enclosed tungsten coil atomizer. A comparison of the analytical performance of Pb in each modifier showed good sensitivity for peak height absorbance measurements [10–11 pg, characteristic mass (m₀)]; the best detection limit (1 µg l^–1, 3σ_blank/slope) and within-run reproducibility (2.2% as RSD) corresponded to Pb in Pd. The proposed procedure was validated with certified reference materials of human hair (BCR CRM 397, GBW-09101 and GBW-07601) and blood (BCR CRM 194 and BCR CRM 195), and all results were in good agreement with the certified values (at a 95% confidence level). Also, the results were comparable to those obtained by ETAAS with a graphite tube. The results obtained with Pd as chemical modifier were accurate and more precise than with phosphates; the mean relative error was 2.5% (0–6.8%) and the mean precision (RSD%) was 5.0% (3.3–6.9%). Recoveries of Pb from spiked human hair and blood were 97.7±8.2% (n=3) and 100.4±8.0% (n=3), respectively.