Optimization of Dispersive Liquid-Liquid Microextraction for Spectrophotometric Determination of Lead in Water

Abstract

In this study, dispersive liquid-liquid micro extraction (DLLME) was developed for extraction and pre-concentration of lead ion (Pb2+) prior to its quantitative determination by UV-Vis spectrophotometer. The metal ion was extracted after making a complex with 1,5- diphenylthiocarbazone. Different experimental parameters affecting the extraction efficiency of the complex by DLLME including types and volume of solvent effect, mass of salt effecting, pH, and centrifugal time were assayed and the optimum conditions were established. Calibration curve was constructed by spiking and extracting distilled water containing Pb2+ at eight concentration levels, ranging from 0.005 - 2 mg/L. The obtained calibration curve has good linearity with a coefficient of determination (r 2 ) 0.9952. The limits of detection (LOD) and quantification (LOQ) of the method were 0.003 and 0.009 mg/L, respectively. The precision studied in terms of intra-day and inter-day at two concentration levels showed acceptable %RSD values that were less than 3% in both cases. Applicability of the method was investigated by analyzing different water samples and demonstrated satisfactory recoveries ranging from 79.1- 108.1%. Generally, the developed DLLME method could be used as attractive alternative for extraction and pre-concentration of the lead as a complex of 5-diphenylthiocarbazone prior to quantitative determination by UV-Vis spectrophotometer.