Electrochemical preconcentration of ultra-trace Cd²⁺ from environmental and biological samples prior to its determination using carbon paste electrode impregnated with ion imprinted polymer nanoparticles

Abstract

Cadmium (Cd) is known as one of the most toxic elements among the heavy metals. This study proposes an electrochemical preconcentration method using the ion imprinted polymer nanoparticles modified carbon paste electrode (IIP-CPE) for the stripping voltammetry determination of Cd2+ in the environmental and biological samples. These IIP NPs were synthesised using ethylene glycol dimethacrylate as the cross-linker, 2,2ʹ-azobisisobutyronitrile as the free radical initiator and 4ʹ-(4-vinylphenyl)-2,2ʹ:6ʹ,2ʺ-terpyridine as the Cd-binding ligand. The calibration plot was linear in the concentration range of 4–500 nM (R2 = 0.9936) with a sensitivity of 918 µA µM−1 cm−2. The LOD based on 3Sb/m (where m is the slope of the calibration curve and Sb is the standard deviation for five blank measurements) was found to be 1.94 nM. The relative standard deviations (RSDs) for single-electrode repeatability and electrode-to-electrode reproducibility were 3.0% and 5.6% (n = 5), respectively. The accuracy of the current method was confirmed by the analysis of urine quality control material (QCM, SeronormTM Trace Elements Urine, REF NO 201205, Norway) and spiked blood, rice and water samples. Recoveries were found to be above 95.0% for all samples, which confirms the good performance of the proposed voltammetry method.