Defect-rich SrAl₂O₄@carbon black composite as a high-performance electrocatalyst for tert-Butylhydroquinone sensing...

The prevalence of synthetic antioxidants in processed foods necessitates the development of sensitive, rapid, and cost-effective analytical methods for their accurate monitoring and quantification. This study describes the facile synthesis of a novel defect-engineered SrAl₂O₄@CB nanocomposite to investigate the sensitive electrochemical detection of tert-butylhydroquinone (TBHQ) in food samples. EIS revealed that the SrAl₂O₄@CB/SPCE exhibited the lowest charge-transfer resistance. Electrocatalytic investigations demonstrated for the first time that defect engineered SrAl₂O₄@CB/SPCEs facilitated superior electron transfer and increased mass transport of reaction by dual pathway mechanism, whereby TBHQ molecular adsorption and OH bond polarization was facilitated by the Lewis acid Sr-O-Al sites on the electroactive surface while CB contributed to the electrocatalytic reaction through π-π stacking and rapid electron delocalization. Under optimized condition (0.1 M phosphate buffer, pH -7.0), the SrAl₂O₄@CB/SPCE sensor showed an analytical performance for TBHQ detection by DPV, including an exceptionally wide linear detection range of 0.01-142.94 μM (R² = 0.995) and an ultra-low detection limit (LOD) of 0.0051 μM. The sensor demonstrated outstanding operational reliability with a repeatability, reproducibility and exceptional long-term stability. Selectivity of the sensor toward TBHQ was demonstrated by interference studies and it was tested in commercially available edible oils using the standard addition method, achieving consistently high recovery rates of (97-103%) with low relative standard deviation (RSD < 4%, n = 3) across all tested matrices.