Simultaneous Determination of Zn, Pb and Cd Ions by Ultrasound-assisted Liquid Phase Micro-Extraction and FFT Voltammetry

In this study, several heavy metal ions (Zn2+, Pb2+ and Cd2+) were extracted and online determined in water samples by ultrasound-assisted hollow fiber liquid phase micro-extraction (HF-LPME) coupled with stripping fast Fourier transform continuous cyclic voltammetry (SFFTCCV) as a novel electroanalytical technique. Initially, the heavy metal ions were extracted through a polypropylene membrane soaked in xylene and bis(2-ethylhexyl)phosphoric acid (DEHPA), into an acceptor solution located in the lumen of a hallo fiber (HF). The analytes were then determined through an electrochemical approach using a micro carbon paste electrode (micro-CPE) as a working electrode placed into the upper end of the HF. The optimum conditions for the proposed method were reached at scan rate of 6 V s−1, stripping potential: 200 mV, stripping time: 5 s, the sample solution pH: 5, the acceptor solution pH: 4, extraction time under the ultrasound irradiation: 60 min, membrane composition: 0.5 M DEHPA in xylene. Limit of detection (LOD) and limit of quantification (LOQ) were determined to be in the range of 0.1-1 and 1-5 ng.mL-1. Furthermore, the recovery percentages of 87%, 62% and 41% were obtained for Zn2+, Pb2+ and Cd2+ ions, respectively. Based on the results, the method presented adequate potential to be used for the simultaneous determination of the stated analytes in the sea, river and well water samples, under optimal conditions.