Highly-sensitive detection of methanol via metal–phenolic film-coated quartz crystal microbalances possessing distinct physicochemical surface profile

Abstract

Alcohol is one of the most widespread mind-affecting substances increasing the internal feeling of happiness, euphoria, conviviality and pleasance, but the improperly distilled (adulterated) beverages containing methanol pose risk to the human health. Measures for preventing the intoxication with counterfeit alcohol comprise point-of-use analysis of the alcohol via portable metal-oxide devices, liquid crystal-based detectors and spectrometric sensors with limited effectiveness due to periodic clogging of the separation column, uncertainties induced by the color of emitted light or unstable signal caused by the different optical transparencies of alcohol containers. Contemporary electronics may provide sustainable solutions to these problems by launching miniature metal–phenolic film-coated quartz crystal microbalances (MPF-QCMs) for selective detection of methanol in spirits; however, the effect of surface profile of the sorptive layer on the sensor response of these devices is unknown. We eliminate this knowledge gap by spin coating metal–phenolic films with different morphology, chemistry, wettability and thickness on the surface of six 5 MHz QCMs and subjecting them to the saturated vapor of methanol, ethanol, isopropanol, water, petroleum ether and ammonium hydroxide. The execution of over hundred experiments shows that the MPF-QCMs discriminate the chemical analytes in a repeatable and reproducible manner depending on their molecular size and acidity, and the morphochemical peculiarities of the solid surface, facilitating the registration of methanol fractions up to three orders of magnitude below the admissible concentrations in spirits. Our results provide scientific advance that has potential to address the global challenge related to the consumption of denatured alcohol.