Simultaneous voltammetric detection of cadmium(II), arsenic(III), and selenium(IV) using gold nanostar-modified screen-printed carbon electrodes and modified Britton-Robinson buffer.

The present work reports a newly developed square wave anodic stripping voltammetry (SWASV) methodology using novel gold nanostar-modified screen-printed carbon electrodes (AuNS/SPCE) and modified Britton-Robinson buffer (mBRB) for simultaneous detection of trace cadmium(II), arsenic(III), and selenium(IV). During individual and simultaneous detection, Cd, As, and Se exhibited well-separated SWASV peaks at approximately - 0.48, - 0.09, and 0.65 V, respectively (versus Ag/AgCl reference electrode), which enabled a highly selective detection of the three analytes. Electrochemical impedance spectrum tests showed a significant decrease in charge transfer resistance with the AuNS/SPCE (0.8 kΩ) compared with bare SPCE (2.4 kΩ). Cyclic voltammetry experiments showed a significant increase in electroactive surface area with electrode modification. The low charge transfer resistance and high electroactive surface area contributed to the high sensitivity for Cd (0.0767 μA (0.225 μg L)), As (0.2213 μA (μg L)), and Se (μA (μg L)). The three analytes had linear stripping responses over the concentration range of 0 to 100 μg L, with the obtained LoD for Cd, As, and Se of 1.6, 0.8, and 1.6 μg L, respectively. In comparison with individual detection, the simultaneous detection of As and Se showed peak height reductions of 40.8% and 42.7%, respectively. This result was associated with the possible formation of electrochemically inactive arsenic triselenide (AsSe) during the preconcentration step. Surface water analysis resulted in average percent recoveries of 109% for Cd, 93% for As, and 92% for Se, indicating the proposed method is accurate and reliable for the simultaneous detection of Cd, As, and Se in real water samples. Graphical abstract.