Rotating gold microwire electrode for the voltammetric detection of mercury and arsenic in shellfish

Abstract

Monitoring mercury (Hg) and arsenic (As) in bivalve shellfish is crucial for ensuring food safety and protecting human health, given the bioaccumulation potential of these toxic contaminants. This study introduces a novel, low-cost, and highly sensitive electrochemical method for the determination of Hg and As in bivalve molluscs, leveraging a unique assembly that incorporates a gold micro-electrode. The electrode's design is characterised by its increased surface area resulting from the spherical geometry, enhancing sensitivity for trace metal detection. Further refinement is achieved through the integration of a conductive coupler, facilitating the electrode's rotation to augment analyte mass transport to the electrode surface, thereby improving the detection limits and overall analysis efficiency. The simplicity of the sensor assembly combined with its capacity for on-site and in situ application, sets a new benchmark for practicality in environmental monitoring tools. After pretreatment and conditioning of the substrate its ability to detect trace levels of As and Hg in certified reference materials and in real shellfish samples after microwave digestion was investigated. The repeatability, linearity, accuracy, and detection limit of the procedure were evaluated. For mercury and arsenic, a short 90 second deposition time resulted in detection limits of 0.3 μg L⁻¹ and 0.21 μg L⁻¹ and a linearity of 0.5 to 100 μg L⁻¹ and 1.0 to 100 μg L⁻¹, respectively. Close agreement with stated values for a certified reference material verified the accuracy and reliability of the analysis.