FAST, NON-DESTRUCTIVE ANALYSIS FOR DETECTING METHANOL IN BEVERAGES, SIMPLE AND REVOLUTIONARY METHODS; THINKING OUTSIDE THE BOX

In Brazil, recent cases of methanol intoxication through ingestion of adulterated alcoholic beverages became nationally notorious. Methanol is highly toxic to humans. Over the last 2 months, 8 deaths were confirmed with more current cases under investigation. Therefore, this work developed new accessible techniques to classify and analyze the chemical adulteration of alcoholic beverages: a) fourier-transform infrared spectroscopy (FTIR), b) diffractive visible light sensor (DVLS) and c) graphene field-effect transistor (GFET) sensor. The results obtained from the FTIR showed a change in the wavelength as methanol concentrations varied from 0,25 to 30% where the methanol had a band in 980 to 1060 cm-1 and ethanol had a band in 1020 to 1060 cm-1, the data analysis resulted in a regression model with a coefficient of determination R2=0.9999 and its application to the beverages samples resulted in a predictive power of Q2=0.7573. DVLS demonstrated that the refractive index of each liquid directly influences the laser diffraction pattern. Pure methanol produced a more open diffraction pattern, while pure ethanol generated a narrower one. When methanol was added to beverage samples, an intermediate diffraction behavior was observed, consistent with a refractive index between the two extremes. However, since methanol’s refractive index is similar to that of water, complementary chemical analyses are essential to distinguish between them, yet the optical method still demonstrated capability to identify adulteration in beverage samples. The GFET results revealed that the vodka sample induced a current suppression of approximately 16-fold relative to the baseline, decreasing from 7.5 µA to 0.47 µA. Conversely, vodka adulterated with 30% methanol exhibited a pronounced increase in current, reaching 21 µA, about 2.8 times above baseline and 45 times higher than neat vodka; these signatures demonstrate the GFET sensitivity to differentiate compositions and effectively detect methanol adulteration in alcoholic beverages, these results corroborate these devices capability to detect and differentiate methanol adulteration in beverages. In this way, the techniques developed and applied in this work are direct, simple, fast, cheap and do not require reagents, thus offering real options to save lives.