Determination of lead in soil by graphite furnace atomic-absorption spectrometry with the direct introduction of slurries

A simple procedure is described whereby 5–20 mg of a powdered soil are mixed with 25 ml of water and, while stirring, 20-µl aliquots of the slurry are pipetted into a graphite furnace electrothermal atomiser. Calibration with aqueous standards gives the total lead concentration of the soil. This is much simpler than the complex hydrofluoric acid digestion procedures normally required to obtain complete recoveries from soil. The over-all precision of the analysis (8% relation standard deviation) is adequate for this application, as is the sensitivity. A characteristic concentration (A= 0.0044) of 0.5 µg l–1 is equivalent to 0.62 µg g–1 soil in a typical slurry.