Ultra-sensitive detection of cadmium and lead in water using crown ether gel electromembrane extraction coupled with miniaturized electrochemical system

Abstract

This study presents the development of an electrochemical technique combined with gel electromembrane extraction (G-EME) for the simultaneous detection of cadmium and lead in environmental water samples. Crown ether (18C6) was added to the gel as a complexing agent and cationic carrier. The electrochemical responses were evaluated using differential pulse anodic stripping voltammetry (DPASV) across various pH levels and deposition times. The most sensitive response (acetate buffer pH 4, deposition time 90 s) was selected for the development of the G-EME process. By applying a 30 V electrical potential across the gel membrane containing 1 % (w/v) of 18C6 for 10 min, positively charged Cd2+ and Pb2+ ions migrated from the donor phase (pH 5.0) through the 18C6@gel membrane (pH 5.0) into the acceptor phase (pH 5.0). This resulted in a linear range from 0.3 to 5 µg/L for Cd2+ and 0.5 to 5 µg/L for Pb2+, with detection limits of 0.10 µg/L and 0.19 µg/L, respectively— up to 120 times more sensitive than direct electrochemical measurements. Furthermore, the proposed technique maintained selectivity for cadmium and lead, despite the presence of other potential heavy metal ions in the environment.