Fundamental studies on improvement of precision and accuracy in flameless atomic-absorption spectroscopy using the graphite-tube atomizer: Lead in whole blood

Some fundamental aspects concerning the formation of ash on a pyrolytic graphite surface and the resulting effects on precision and accuracy in flameless AAS, have been examined for the determination of lead in whole blood. The nature and composition of the ash from whole blood and the state of the pyrolytic graphite surface have been observed with the aid of a scanning electron microscope and non-dispersive X-ray microprobe analyser. The use of nitric acid to separate the analytical peak from the matrix peak, an examination of high-temperature clearing of the matrix, and removal of ash remnants between each analysis are reported. A procedure to improve precision and accuracy in flameless AAS using the graphite-tube atomizer is reported.