Abstract
A simple liquid-liquid microextraction termed as vortex-assisted liquid-liquid microextraction (VLLME) coupled to flame atomic absorption spectrometry for lead (Pb) determination is achieved through phase-partitioning phenomena of ionic surfactants in aqueous solution. In this procedure, the hydrophobic chelate of Pb with 1-(2-pyridylazo)-2-naphthol (PAN) was extracted into the fine droplets of 1-butyl-3-methylimidazolium hexafluorophosphate [C(4)mim][PF6], while using Triton X-100 (TX-100) as dispersing medium. Several variables including [C(4)mim][PF6] volume, pH of sample, TX-100 volume, concentration of PAN, centrifugation time and rate were considered to be studied. At optimum experimental values of significant variables, detection limit (LOD) and the enhancement factor (EF) were observed to be 0.307 mu g L-1 and 54.2, respectively. The relative standard deviation (RSD) of 10 mu g L-1 Pb was 4.09%. The coexisting ions showed no obvious negative outcome on Pb preconcentration. Validation of the developed method was carried out by Pb determination in "NIST-SRM 1515 Apple leaves'' standard reference material and the results were found in good agreement with the certified values. The method was applied satisfactorily for the preconcentration of Pb in acid digested samples.