Slurry sampling determination of lead after solid phase extraction

Recently, the determination of trace metal ions in many samples has gained importance because of growing environmental pollution. For the determination of trace elements at low concentrations, graphite furnace atomic absorption spectrometry is an atomic spectroscopic technique with high sensitivity and selectivity. But interferences still have effects upon the determination of these elements. Hence, the use of separation/pre-concentration (enrichment) method is necessary to determine the trace elements by atomic absorption spectrometry, when the concentration of the analyte is too low to be determined directly and/or when interferences due to the matrix cannot be compensated. In this study, for the determination of lead in tab water samples, a slurry sampling method was proposed by GFAAS. At first, Pb was collected on montmorillonite by batch technique. After separation of the liquid phase, the solid phase was slurried in a mixture of 0.1% Triton X-114 and 0.1 mol/L HNO3 in order to obtain quantitative recoveries. Then the slurry was directly pipetted into graphite furnace without elution. Optimum conditions for quantitative sorption and those for preparing and introducing the slurry into graphite furnace were studied. The risks of elution step on the precision and recovery were eliminated. A 50-fold enrichment factor could be reached by this technique. The proposed method was validated by the analysis of waste-water (HPS-CWW-TM-E) standard reference material. Furthermore, the Pb in water samples (tap and river) were collected from different regions of Turkey was determined. The obtained results showed that this technique is applicable to analyze the various samples containing the trace amount of Pb. The suggested method is a highly accurate, fast practical seperation/enrichment method and the risk of contamination is low. The limit of detection (3σ; N=10) and characteristic concentration of the method for Pb were 0.46 and 1.13 mg/L, respectively.