Redefining the monitoring of antioxidants: Interfacial charge redistribution in SrTiO3@GCN nanocomposite for improved electrochemical detection of propyl gallate in food matrices

The synthetic food preservative propyl gallate (PG), which is added to oils and other processed foods, has raised concerns among researchers due to its toxicity and environmental impacts. This study reports a new electrochemical sensor based on the heterostructured strontium titanate-graphitic carbon nitride (SrTiO₃@GCN) nanocomposite that detects PG quickly and selectively even in complicated food matrices. SrTiO₃ particles were prepared by a sonochemical route and then ultrasonicated with exfoliated GCN sheets to yield a porous hybrid with very high surface area. Since the assembly creates an internal electric field and rearranges charge at the interface, the SrTiO₃@GCN material shows better conductivity, fast redox response, and stronger adsorption of PG. Electrochemical tests showed that the glassy carbon electrode modified with SrTiO₃@GCN delivered enhanced current response and reduced the resistance to charge transfer. The synergistic effect of SrTiO₃ and GCN in promoting electron transfer as well as active sites for PG interaction increases the sensitivity of the sensor significantly. When experimental parameters were optimized, the sensor produced a broad linear response between 5.0 and 1300.0 μM and a very low limit of detection, measured at 0.014 μM. In the presence of common food matrix components, the device retained high reproducibility, clear selectivity, and remarkable long-term operational stability. Analyses of peanut butter, noodle samples, and cooking oil yielded recovery rates of 96 to 104 %, underscoring the sensors usefulness in real applications. Overall, the work advances a heterointerface-driven electrocatalytic approach for tracking additives in food and presents a promising tool for at-line safety tests.