Slurry sampling for the determination of lead, cadmium and thallium in soils and sediments by electrothermal atomic absorption spectrometry with fast-heating programs

To determine the lead and cadmium content of soils and sediments, the samples are suspended in water containing 5% (vv) concentrated hydrofluoric acid before injected into the electrothermal atomizer. For thallium determination a 30% hydrofluoric acid solution is used as the suspension medium. In accordance with fast-heating methodology, the conventional ashing step is replaced by a modified drying stage performed by programming the instrument to 400°C. No modifier other than hydrofluoric acid is required. Calibration is performed directly using aqueous standards for cadmium and lead determination. For thallium the standard additions method is recommended. The results obtained for five certified reference materials show the reliability of the procedures.