Tetradecyl(trihexyl)phosphonium chloride ionic liquid single-drop microextraction for electrothermal atomic absorption spectrometric determination of lead in water samples

A highly efficient single-drop microextraction (SDME) procedure using a low-cost room temperature ionic liquid (RTIL),i.e, tetradecyl(trihexyl)phosphonium chloride (CYPHOS (R) IL 101), for Pb determination at trace levels in real water samples was developed. Lead was chelated with 2-(5-bromo-2-pyridylazo)5-diethylaminophenol (5-Br-PADAP) reagent and extracted into a 4 mu L. microdrop of CYPHOS (R) IL 101. The RTIL drop was directly injected into the graphite furnace of the electrothermal atomic absorption spectrometer (ETAAS). Under optimal microextraction conditions, a preconcentration factor of 32 was achieved with only 1.5 mL of sample resulting in a phase-volume ratio of 375. The limit of detection (LOD) obtained was 3.2 ng L-1 and the relative standard deviation (RSD) for 10 replicates at 0.5 mu g L-1 Pb2+ concentration level was 49%, calculated at peak heights The calibration graph was linear from concentration levels near the detection limits up to at least 4.5 mu g L-1 with a correlation coefficient of 09996. The accuracy of the methodology was evaluated by analysis of a certified reference material (CRM). The method was successfully applied to the determination of Pb in tap, mineral, well and river water samples. (C) 2009 Elsevier B.V. All rights reserved.