The COVID-19 pandemic has increased dramatically the demand for hand sanitizers. A major concern is their adulteration with methanol that caused more than 700 fatalities in Iran and U.S.A. (since Feb. 2020). In response, the U.S. Food and Drug Administration (FDA) has restricted the methanol content in hand sanitizers to 0.063 vol% and blacklisted 194 products (as of Oct. 1, 2020). Here, we present a low-cost, handheld and smartphone-assisted device that detects methanol selectively in hand sanitizers between 0.01-100 vol% within two minutes by headspace analysis. It features a nanoporous polymer column that separates methanol from confounders by adsorption (i.e. van-der-Waals forces) rendering it selective. A chemoresistive gas sensor detects the methanol. When tested on seven pure and spiked commercial sanitizers (total 76 samples), methanol was quantified accurately, in excellent (R<sup>2</sup> = 0.99) agreement to "gold standard" gas chromatography. Most importantly, methanol quantification was hardly interfered by different sanitizer compositions (e.g. 2-propanol, ethanol, butanone, glycerin, aloe vera essence, various odorants and colorants) and gel-like viscosity while other potential contaminants (e.g. 1-propanol) were recognized as well. This device meets an urgent need for distributed and on-site methanol screening by authorities (e.g. customs, police), health product distributers and even laymen. <br>
Highly selective detection of methanol over ethanol by a handheld gas sensor