Single drop microextraction combined with graphite furnace atomic absorption spectrometry for determination of lead in biological samples

Single drop microextraction combined with graphite furnace atomic absorption spectrometry is introduced for the determination of trace lead in water samples. A drop of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) dissolved in benzene was held at the tip of a microsyringe and immerged into the sample solution which was stirred, the solvent drop interacts with the sample solution, and the analyte was extracted into the drop and concentrated. After extracting for a period of time, the drop was retracted into the microsyringe and directly injected into graphite furnace for GFAAS determination of Pb. Several factors affecting the extraction efficiency, such as pH of sample solution, drop volume, stirring rate and extraction time, were optimized. Under the optimized conditions, an enhancement factor of 16 was achieved, and the detection limits for Pb were 25 ngL(-1). The relative standard deviation for seven replicate determination of 10 ng mL(-1) Pb was 6.1%. The method was applied to determine trace Pb in biological samples with satisfactory results.