Determination of lead in blood by atomic absorption spectrometry with electrothermal atomisation

Abstract

A method is described for the routine determination of lead in whole blood by electrothermal atomisation from a L'vov platform and atomic absorption spectrometry. The sample preparation is a simple 1 + 19 dilution with a diluent containing a mixture of NH₃ solution, NH₄H₂PO₄ and (NH₄)₂H₂EDTA. Further chemical modification is achieved using in situ oxygen ashing during electrothermal sample decomposition at 550 °C. Desorption of oxygen at 950 °C without losses of lead gives tube lifetimes of 200–250 firings. The calibration graph, established with matrix-matched standards and using integrated absorbance measurements, is linear for concentrations up to 5 µmol l^–1. The detection limit is 8.3 × 10^–12 g or 0.08 µmol l^–1 of lead in blood. The within- and between-run precisions are 6.9% and 7.3%, respectively, at 0.5 µmol l^–1 of lead, and the accuracy of the method is demonstrated by the excellent agreement with the results of micro-sampling flame atomic absorption spectrometry and with group mean values in external quality assessment programmes.