RAPID FURNACE PROGRAMS FOR THE SLURRY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF CHROMIUM, LEAD AND COPPER IN DIATOMACEOUS-EARTH

The samples are suspended in water containing hydrofluoric acid and then injected into the electrothermal atomizer. To decrease the heating programme time, the drying step is performed at higher than usual temperatures, and ashing and clean-up steps are omitted. Simple aqueous standards are used for calibration. The results reveal no significant differences at the 95% confidence level (Wilcoxon T-test and use of regression lines) from those obtained using acid digestion of the samples. The analysis of certified reference materials shows the reliability of the approach. The use of hydrofluoric acid solutions as the suspending media is confirmed to be a reliable way of prolonging the lifetime of platforms and tubes when slurries prepared from samples with a high silica content are used.