CHEMICAL MODIFIERS IN A TUNGSTEN COIL ELECTROTHERMAL ATOMIZER - PART 1 - DETERMINATION OF LEAD IN HAIR AND BLOOD

A critical evaluation of the use of chemical modifiers [(NH4)(2)HPO4, NH4H2PO4 and Pd as Pd(NO3)(2)] for the determination of Pb in acid-dig ested blood and hair was performed in a non-enclosed tungsten coil ato mizer. A comparison of the analytical performance of Pb in each modifi er showed good sensitivity for peak height absorbance measurements [10 -11 pg, characteristic mass (m(0))]; the best detection limit (1 mu g l(-1), 3 sigma(blank)/slope) and within-run reproducibility (2.2% as R SD) corresponded to Pb in Pd. The proposed procedure was validated wit h 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 result s were in good agreement with the certified values (at a 95% confidenc e level). Also, the results were comparable to those obtained by ETAAS with a graphite tube. The results obtained with Pd as chemical modifi er were accurate and more precise than with phosphates; the mean relat ive 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.