Electrochemical pre-treatment of graphite electrode as a green modification strategy for sensitive voltammetric determination of pyrazinamide

Graphite electrode (GE) is an alternative, commercially available, and ready-to-use electrode for a wide range of electroanalytical applications. Electrochemical activation of GE is an efficient step in the preparation of high-performance electrochemical (bio-)sensors. In the present study and the continuation of our research project in the lab about the effect of activation of GE surface on the alteration of electrode structure (formation of different functional groups) and subsequent influence on the sensitive determination of various analytes, a simple and low-cost electrochemical sensor based on the graphite electrode extracted from the battery is developed to measure pyrazinamide (PZA), an antibiotic that is mostly used in treating tuberculosis. Two activation strategies including potentiostatic and potentiodynamic were tested and according to the results, utilizing the potentiodynamic strategy represents good performance in the sensitive detection of PZA. Morphological characterization of activated GE was done using scanning electron microscopy (SEM). A comparison of the effective surface area of the activated and bare GE revealed that the activation process increased the effective surface area of the electrode by 1.6 times. The electroanalytical response of PZA at the activated GE surface was studied utilizing cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The impact of various parameters on the reduction current response of PZA was investigated and it was found that the developed electrochemical sensor can successfully determine PZA within the concentration ranges of 1.31–29.81 µM under the optimized conditions and the limit of detection (LOD) was calculated to be 0.89 µM as well. Analysis of real samples such as pharmaceutical formulations and human serum demonstrated excellent recoveries, revealing the promising capability of the proposed sensor for PZA determination.