High-sensitivity detection of brilliant blue by disposable chitosan–biochar electrochemical sensors

This research created a disposable electrochemical sensor utilizing a chitosan-biochar (CS-H500) composite-modified glassy carbon electrode (GCE) for the very sensitive detection of brilliant blue (BB) in food products. The CS-H500 composite dispersion was synthesized using the ultrasonic dispersion method, while quantum chemical simulations clarified the adsorption mechanism of BB molecules on the electrode surface <i>via</i> π-π conjugation and electrostatic interactions. Optimized experimental settings comprised the following: 16 μL of CS-H500 dispersion, 300 seconds of accumulation period, and a pH 7.0 phosphate buffer. The results indicated that chitosan (CS) markedly enhanced the dispersibility of biochar, augmenting the effective surface area of the modified electrode by 2.53 times (0.179 cm²) in comparison with that of the bare GCE. The sensor demonstrated a linear detection range of 1.0 × 10^-6 to 1.0 × 10^-4 mol L^-1 for BB, with a detection limit of 1.0 × 10^-7 mol L^-1 (S/N = 3), acceptable recoveries (91.49%-102.18%), and commendable reproducibility (RSD = 8.01%). Interference studies validated significant selectivity against citric acid, glucose, prevalent metal ions, and proficient differentiation from mixed pigments such as sunset yellow (SY) and fluorescein sodium (FS). The analysis of real beverage samples confirmed its reliability. This disposable electrode design streamlines operation, prevents cross-contamination, and offers an effective option for on-site monitoring of food additives.