Iridium as permanent modifier in the determination of lead in whole blood and urine by electrothermal atomic absorption spectrometry

The behavior of Iridium as a thermally deposited permanent modifier for the determination of lead by GFAAS was studied. The iridium coating procedure was optimized using a two-level factorial design. Using the optimized coati ng procedure, up to 1100 firings were possible with the same coating withou t sensitivity losses. The system was used in the determination of lead in w hole blood and urine. A mixture of 0.1% Triton X-100 and 0.2% nitric acid w as used as diluent. Pyrolysis temperature was 800 degreesC for both matrice s. Spiked, low-level samples were used for calibration. Under these conditi ons, no significant difference was found in comparison to the results obtai ned using a validated conventional modification procedure employing phospha te as modifier. Also, good agreement between found and certified/reference values were observed in the analysis of certified and commercial quality co ntrol materials, respectively. Such agreement was observed even using a 110 0 times fired Ir coated platform-graphite tube assembly. (C) 2001 Elsevier Science B.V. All rights reserved.