Sensitive Detection of Theophylline Using a Modified Glassy Carbon Electrode with g-C₃N₄

Target analyte determination at deficient concentrations is crucial for several industries, including the food, pharmaceutical, and environmental protection sectors. A simple glassy carbon electrode-modified graphitic carbon nitride (g-C₃N₄/GCE) was presented here to measure theophylline (TP) in the sample precisely. After carefully analyzing pH, we suggest a reaction mechanism and discover that TP oxidation is stable across a broad pH range, especially in neutral environments. Utilizing differential pulse voltammetry (DPV) and cyclic voltammetry (CV), the electrochemical oxidation behavior of TP at the g-C₃N₄/GCE was examined. The established electrochemical sensor exhibited admirable electrocatalytic motion near the oxidation of TP in 0.1 M PBS medium. When operating in optimal conditions, the sensor demonstrated high sensitivity for TP determination. The sensitivity of the fabricated electrode is 10.13 µA. µM^− 1 with a detection limit of 0.043µM (S/N = 3), the oxidation peak current of TP exposed a virtuous linear relationship with its concentration in the range from 5.2 to 118µM. For the measurement of TP, the modified electrode demonstrated good repeatability, long-term stability, and excellent sensitivity with respectable recoveries; additionally, recovery values are compared with HPLC methods.