A β-cyclodextrin/porous graphene ink electrode for smartphone-assisted electrochemical Hg²⁺ sensing

A novel portable electrochemical sensor for Hg²⁺ detection was developed, featuring integration with a smartphone-based potentiostat and utilizing a β-cyclodextrin-coated porous graphene ink-modified screen-printed electrode (β-CD/P-Gi/SPE). The use of β-cyclodextrin enhances molecular recognition and selectivity for Hg²⁺, while porous graphene ink improves conductivity and sensitivity, addressing limitations of existing electrode materials. Comprehensive characterization using SEM, EDX, FT-IR, and Raman spectroscopy confirmed the successful incorporation of the β-CD polymer film onto the P-Gi. The electrochemical properties of the modified electrode were evaluated using electrochemical impedance spectroscopy and cyclic voltammetry. The adsorptive anodic stripping voltammetry (AdASV) condition was also optimized. Under optimal conditions, AdASV demonstrated that the oxidation peak current was linearly proportional to the Hg²⁺ concentration in the range of 0.50-80 μg mL^-1 with a detection limit of 0.11 μg mL^-1. Furthermore, the sensor exhibited excellent reproducibility, sustained long-term stability, and a fast current response. To demonstrate the practical applicability of the proposed sensor, the proposed sensor successfully determined Hg²⁺ in skin whitening creams.