Interspersed of Scheelite-Type BaWO₄ Nanoparticles Decorated on CNF for the Electrocatalytic Sensing of Theobromine in Food Products

Methylxanthines (MTX) are purine alkaloids commonly present in the diet. Theobromine (TBR: Theobroma cacao or T. cacao) is a second important purine metabolism in MTX. It naturally occurs in nonalcoholic beverages to stimulate the central nervous system. When consumed in high quantities, it has some negative impacts such as weight gain and addictions. Thus, the development of well-organized electrocatalysts that can monitor and trace the level detection of TBR in food products is urgently required. In this study, a simple means of synthesizing scheelite-type barium tungstate (BaWO4) nanoparticles integrated into carbon nanofiber (CNF) via a sonochemical process is discussed. BaWO4@CNF, as a nanocomposite modified on a glassy carbon electrode (GCE), showed better electrocatalytic activity oxidation in the potential range of 0.9–1.6 V. Noteworthy, the proposed BaWO4@CNF/GCE sensor exhibited an ultralow detecting limit (LOD: 5.2 nM) with a linear range of 0.01–1726 μM and high sensitivity of 2.52 μA μM–1 cm–2 by different pulse voltammetry (DPV) methods. The modified electrode has been applied for anti-interfering ability, repeatability, and stability studies. The practical applicability of the sensor was tested for the quantitative analysis of TBR in coffee and dark chocolate with satisfactory recoveries. Therefore, the hybrid nanocomposite provides a significant potential candidate for the electrochemical detection of food products for public health.