Origin of double-peak signals for trace lead, bismuth, silver and zinc in a microamount of steel in atomic-absorption spectrometry with direct electrothermal atomization of a solid sample in a graphite-cup cuvette.

Atomic-absorption signals of trace lead, bismuth, silver and zinc in steel, obtained by directly atomizing one sample particle, were found to consist of a small first peak and a large second peak. It was concluded that the first peak was caused by the analyte element existing around the grain-boundaries of the steel and near the sample surface and the second by the fraction of the analyte element existing within the crystal grains of the steel.