Development of a method for the voltammetric determination of ascorbic acid on a palladium doped carbonaceous electrode

Ascorbic acid (AA) is a vital antioxidant with critical roles in human health, including immune system support and protection against oxidative stress. Accurate and sensitive determination of AA is essential in clinical diagnostics, pharmaceutical analysis, and food quality control. In this study, a novel voltammetric method was developed using a glassy carbon (GC) electrode modified with palladium-doped carbonaceous material for AA detection. A mixture of equal amounts of raw coal tar pitch (r-CTP) and glass fiber (GF) was pyrolyzed in a high-temperature furnace at 1000°C for 1 h, with a heating rate of 10°C/min under a nitrogen atmosphere. The resulting carbonized material was ground using a planetary ball mill (Retsch, PM100), and palladium nanoparticles (PdNPs) were then doped onto the material via the sol-gel method. The obtained material is denoted Pd/CTP-GF. Pd/CTP-GF was characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The glassy carbon (GC) electrode modified with Pd/CTP-GF was characterized by cyclic voltammetry (CV). A method was developed for the determination of ascorbic acid using differential pulse voltammetry (DPV) on the Pd/CTP-GF modified GC electrode. The detection limit (S/N=3) of the developed method was determined to be 5 nM. The intraday and interday precision and accuracy of the method were also evaluated. In addition, the interference of dopamine, uric acid, and certain cations on ascorbic acid was investigated. In real sample applications, the developed method achieved a recovery of over 95% for ascorbic acid in orange juice samples. Keywords: Ascorbic acid; differential pulse voltammetry; palladium nanoparticle; carbonaceous electrode.