Determination of Trace Pb in Environmental Samples by GF-AAS after Microsphere Phase Separation Extraction

A novel method is described for preconcentration and separation of trace Pb in environmental samples such as water, soil, plant and sediment using a microsphere phase separation extraction. After complexation with 2-[5-Bromo-2-pyridylazo]-5-diethylamino-phenol (5-Br-PADAP) in alkalescent medium, the analytes are extracted to 1-octanol in the present of co-solvent alcohol, and then adding water to change the phase ratio, the contained 5-Br-PADAP-Pb microsphere phase (200 muL) separates out from the homogeneous solution, later the microsphere introduced into the graphite furnace (GF) and detected by atomic absorption spectrometry (AAS). The graphite furnace apparatus conditions such as pyrolysis or atomization temperature and the chemical variables affecting the separation phase were optimized. Detection limit (3 sigma) of 0.05 mug/L, along with enrichment factors of 35 for Pb was achieved. The develop method was applied to the determination of trace lead in a series environmental reference materials. All of the results were found to be in reasonable agreement with the certified values. This simple method shows a great potential for determination other trace metals in environmental samples.