Obtenção e caracterização de filmes de dióxido de titânio nanoestruturado modificados com óxidos mistos de cobre para detecção e quantificação de hidroximetilfurfural

Abstract

The adulteration of honey with sugars is a significant issue that compromises quality and food safety, making it difficult to detect. The presence of high concentrations of hydroxymethylfurfural in honey is an indicator of adulteration or inadequate processing and storage conditions. This study aimed to develop nanostructured titanium dioxide films modified with mixed copper oxides for the detection and quantification of HMF using cyclic voltammetry and differential pulse voltammetry techniques. The films were synthesized by potentiostatic anodization and calcined at 450 ˚C to obtain the anatase crystalline phase. Subsequently, they were self-doped in Tris-HCl and phosphate buffer solutions by applying a reduction potential of -1,4 V, converting titanium ions from oxidation state +4 to +3. The mixed copper oxides were incorporated by pulsed electrodeposition using 200 cycles of cathodic pulses. Structural characterization of the films was performed using scanning electron microscopy, Raman spectroscopy, and X-ray diffraction, confirming the formation of organized nanotubes in the anatase phase. Electrochemical analy- ses in Tris-HCl and phosphate buffer solutions indicated that self-doping in phosphate buffer increased the electrical conductivity of the films, enhancing HMF detection. The electrochemical behavior of the analyte was evaluated, revealing an adsorptive interaction with the sensor. This interaction is associated with the formation of intermediate complexes that catalyze the analyte’s oxidation. An analytical curve was constructed by differential pulse voltammetry in the range of 0,006 to 500 ppm, using pure electrolyte and honey samples to assess matrix effects. Based on analyses in honey samples, a determination coefficient of 94,12% was obtained, with detection and quantification limits of 0,013 and 0,039 ppm, respectively. The developed film demonstrated high sensitivity, selectivity, repeatability, and stability, being validated for real honey sample analysis. Comparison with the modified White method showed consistent results, with the advantage that the sensor is insensitive to turbidity, eliminating the need for sample clarification4a feature that makes it particularly useful for analyzing dark-colored honey. In conclusion, the self-doped titanium dioxide film modified with mixed copper oxides proved to be an efficient, accurate, and cost-effective tool for detecting and quantifying HMF in honey, standing out as a viable and robust alternative to conventional analytical techniques.