DISPLACEMENT-DISPERSIVE LIQUID-LIQUID MICROEXTRACTION BASED ON SOLIDIFICATION FLOATING ORGANIC DROP TRACE AMOUNTS OF LEAD IN WATER SAMPLE PRIOR TO FLAME ATOMIC ABSORPTION SPECTROMETRY DETERMINATION

Abstract

In this study, a novel method using displacement-dispersive liquid-liquid microextraction based on solidification of floating organic drop in complicated samples prior to flame atomic absorption spectrometry determination was developed. This method involves two consecutive dispersive liquid-liquid microextraction based on solidification. In step I, Zn(II) ions reacted with ammonium pyrrolidine dithio carbamate (APDC) to form Zn-APDC complex and was extracted with the solidified floating organic drop microextraction procedure using 1-undecanol (extraction solvent) and ethanol (dispersive solvent). In step II, after centrifugation and solidification, the separated drop was dissolved in dimethylformamide (DMF) and then dispersed into the sample solution containing lead ion and another dispersive liquid-liquid microextraction based on solidification procedure was carried out. Due to the greater stability of Pb-APDC, Pb displaces Zn from the preextracted Zn-APDC and preconcentration of Pb was achieved. Under the optimized conditions, the calibration curve was linear in the range of 4-700 ng mL-1 with detection limit of 0.7 ng mL-1(3σ b ). The relative standard deviation of ±1.6% was obtained (n=7) and the enrichment factor was found to be 35.0.