Determination of trace levels of lead in water samples by graphite furnace atomic absorption spectrometry after dispersive liquid-liquid microextraction based on solidification of floating organic drop

Abstract

A novel and environmentally friendly method has been developed for the determination of lead (Pb) by dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFOD) combined with graphite furnace atomic absorption spectrometry (GFAAS). In this method, 1-undecanol, which is of low density, low toxicity and has a proper melting point near room temperature, was used as the extraction solvent instead of a highly toxic organic solvent, and the phase separation was enhanced by solidification of the floating organic phase. Some parameters influencing the DLLME-SFOD extraction efficiency of Pb and its subsequent determination, such as type and volume of extraction and dispersive solvent, pH of sample solution, concentration of the chelating agent, extraction time and coexisting ions, were systematically investigated. Under the optimized conditions, the calibration graph exhibited good linearity over the Pb concentration range of 0.05-20.0 ng mL-1 with a correlation coefficient (r) of 0.9975. The detection limit of this method for Pb was 18 ng L-1 with an enhancement factor of 77, and the relative standard deviation (RSD) was 3.8% at the 1.0 ng mL-1 Pb level. The method was successfully applied to the determination of trace amounts of Pb in water samples.