Polytetrafluorethylene membrane-based liquid three-phase micro extraction combined with in situ differential pulse anodic stripping voltammetry for the determination of cadmium ions using Au-nanoparticles sol-gel modified Pt-wire

Abstract

In this study, one particular application of in situ pulse anodic stripping voltammetry and polytetrafluoroethylene membrane-based liquid three-phase micro extraction is presented for the micro extraction and quantification of cadmium(II) ions in trace levels. The main factors influencing on preconcentration and micro extraction of cadmium ions such as organic solvent, aqueous feed solution pH and acceptor phases, complexing agent concentration, time of extraction and stirring were examined and discussed in details. The design voltammetric cell was made of three microelectrodes inserted into an extraction cell, containing acceptor solution and then the voltammetric analysis was performed in situ during the extraction time. The enrichment factor and the relative standard deviation, under the optimized conditions, were 15 and 1.7% (n = 5), respectively. The obtained calibration curve was in the range of 1.0-250 nmol L-1 CdII with a regression coefficient of 0.9980. The limit of detection was found 0.1 nmol L-1. Due to the high total effective area of the gold nanoparticles and the low analyte concentration, the anodic stripping voltammetric method relies exclusively on the underpotential deposition and stripping process of CdII on gold, with little hydrogen evolution during deposition at -0.40 V and no gassing at the stripping peak near 0.0 V vs. Ag/AgCl. The good selectivity for the underpotential deposition/stripping method is one of advantages of the proposed method. The efficiency of the method for determination of cadmium(II) for real samples was checked using fish and rice samples.