Fluorometric and colorimetric dual-mode detection of tert-butylhydroquinone in food samples using Mn3O4/AuNPs composite nanozyme and Cu,I-doped carbon dots.

Highly mimetic enzymatic Mn₃O₄/AuNPs composites were prepared, which catalyze the oxidation of tert-butylhydroquinone (TBHQ) to red 2-tert-butyl-1,4-benzoquinone (TBBQ) for TBHQ detection. Absorbance at 487 nm (A₄₈₇) correlates linearly with TBHQ concentrations in the range of 0.52-50 μg/mL, with a limit of detection (LOD) of 0.063 μg/mL, and a limit of quantification (LOQ) of 0.21 μg/mL. TBBQ quenches the fluorescence of copper/iodine-doped carbon dots (Cu,I-CDs) at 500 nm via the inner filter effect (IFE), forming an "on-off" fluorescence probe for TBHQ. TBHQ concentration correlates linearly with the fluorescence intensity difference (F₀ - F) in the range of 0.31-54 μg/mL, with an LOD of 0.054 μg/mL and an LOQ of 0.18 μg/mL. This study uses a dual-mode detection approach to determine TBHQ in various food samples, with recovery rates ranging from 82.5% to 103.0%. The method is sensitive, accurate, cost-effective, and suitable for the rapidly analyzing of TBHQ in food.