Efficient Detection of Xanthine Content in Edible Mushrooms Using Electrochemical Sensors Based on g-C₃N₄

This study aims to construct a highly sensitive, reliable, and low-cost electrochemical sensor based on graphitic carbon nitride (g-C₃N₄) modified materials for efficient and convenient detection of purine content in food. The g-C₃N₄ material was fabricated through a high-temperature calcination method, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The results indicate that the g-C₃N₄ material exhibits a two-dimensional sheet-like nanostructure, characterized by a high degree of graphitization, abundant N-functional group content, and a specific surface area of 61.35 m²/g. An electrochemical sensor (g-C₃N₄/GCE) was fabricated by modifying a glassy carbon electrode (GCE) with the composite material. Under optimal conditions (pH 5.5, enrichment potential of 0.3 V, and enrichment time of 5 min), the peak current of the sensor demonstrated a favorable linear relationship with the concentration of xanthine. Within the low concentration range of 0.5~5 μmol/L, a linear relationship was established as Ipa=0.051C_XA+4.034 (where Ipa represents the peak current and C_XA denotes the xanthine concentration), with a coefficient of determination R²=0.997. In the high concentration range of 5~200 μmol/L, the linear relationship was determined to be Ipa=0.310C_XA+2.859, with R²=0.990. The minimum detection limit (LOD) was calculated to be 0.28 μmol/L. According to this sensor, the xanthine content in shiitake mushrooms, tea tree mushrooms, and wood ears were 307.50 mg/100 g, 229.22 mg/100 g, and 47.27 mg/100 g, respectively. Compared with the commonly used high-performance liquid chromatography method, the g-C₃N₄ electrochemical sensor exhibits good stability, with a relative standard deviation (RSD) of 1.45%~3.69%, and the operation is simple, which can be used for the detection of xanthine in edible mushrooms.