Determination of Pb in Geological Materials by Heat Extraction Slurry Sampling ET-AAS

Lead (Pb) is a non-essential but extremely noxious metallic element, which is important for the assessment of environmental pollution. A simple and high throughput method involving fast heat extraction slurry sampling electrothermal atomic absorption spectrometry (HESS-GFAAS) was developed to detect trace Pb content in geological standard reference materials (SRMs). Compared with the traditional digestion method, the HESS-GFAAS method greatly reduces the time of sample pretreatment. The HESS-GFAAS technique improved Pb recovery and precision compared to conventional slurry sampling techniques. This optimized HESS-GFAAS procedure was performed as follows: first, the sample was added into 1 mL HNO3, 1 mL HCl and 1 mL HF, followed by heating for 30 min at 120 degrees C on a heating block; Next, dilute the solution with 50 mL water, and finally, the solution was introduced into a graphite tube with Pd(NO3)(2)-NH4H2PO4 as the mixed matrix modifier and analyzed by the GFAAS with a Pb electrodeless discharge lamp (EDL). To eliminate the interface of the geological sample matrix, the method of additions calibrate was used for Pb determination in geological samples. The results for 20 of these materials were in good agreement with the reference values. The characteristic mass and limit of detection for Pb based on the integrated absorbance for a 0.2% (m/v) sample were 14.8 +/- 0.8 pg and 0.035 mg kg(-1), respectively. The accuracy (96.05-102.4% recovery) and precision (0.13-2.07%) of this procedure are illustrate by the results obtained for the 20 geological reference materials. The proposed method shows great potential for the determination of trace Pb in geological samples.