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Metal Oxide Sensor Helps Measure Methanol in Alcoholic Beverages

Scientists at ETH have created an economical, handheld measuring device that can differentiate between methanol and potable alcohol. The device provides a fast and simple technique of detecting adulterated or tainted alcoholic beverages and can detect methanol poisoning in exhaled breath.

Women in India sell home-brewed alcohol, which may contain toxic amounts of methanol. (Image credit: Shutterstock/Steve Estvanik)

Methanol is occasionally termed as ethanol’s lethal twin. While the latter is the intoxicating component in wine, schnapps, and beer, the former is a chemical that turns very toxic when metabolized by the human body. Even a comparatively small amount of methanol can result in blindness or even prove deadly if not treated soon.

Cases of poisoning caused by ingestion of alcoholic beverages contaminated with methanol happen frequently, particularly in emerging and developing nations. This is because alcoholic fermentation also creates small amounts of methanol. Every time alcohol is incompetently distilled in backyard operations, relevant quantities of methanol may wind up in the liquor.

Beverages that have been adulterated with windscreen washer fluid or other liquids comprising methanol are another possible cause of poisoning.

Beverage Analyses and the Breath Test

Thus far, methanol could be differentiated from ethanol only in a chemical analysis laboratory. Even hospitals need comparatively large and costly equipment to diagnose methanol poisoning.

These appliances are rarely available in emerging and developing countries, where outbreaks of methanol poisoning are most prevalent.

Andreas Güntner, Research Group Leader, Particle Technology Laboratory, ETH

Particle Technology Laboratory is headed by ETH Professor Sotiris Pratsinis. Güntner is also a researcher at the University Hospital Zurich.

At present, he and his colleagues have built a low-cost handheld device based on a small metal oxide sensor. It can detect adulterated alcohol in two minutes by “sniffing out” ethanol and methanol vapors from a beverage. Furthermore, the tool can be used to identify methanol poisoning by examining the exhaled breath of a patient. During emergencies, this helps ensure that suitable steps are taken without any delay.

Separating Methanol from Ethanol

There is nothing novel about employing metal oxide sensors to measure alcoholic vapors. But, this technique was incapable of distinguishing between various alcohols, such as methanol and ethanol.

Even the breathalyser tests used by the police measure only ethanol, although some devices also erroneously identify methanol as ethanol.

Jan van den Broek, Study Lead Author and Doctoral Student, ETH

First, the ETH researchers created a highly sensitive alcohol sensor using nanoparticles of tin oxide doped with palladium. Secondly, they used a trick to distinguish between ethanol and methanol.

Rather than examining the sample directly using the sensor, the two types of alcohol are first divided in an attached tube filled with a porous polymer, through which the sample air is drawn out by a small pump. Since methanol molecules are smaller, they pass through the polymer tube more rapidly than ethanol.

The measuring device proved to be remarkably sensitive. In laboratory experiments, it detected even trace quantities of methanol contamination selectively in alcoholic drinks, down to the low legal limits. Additionally, the researchers examined breath samples from a person who had earlier consumed rum. For test purposes, the scientists then added a small amount of methanol to the breath sample.

Patent Pending

A patent application has been filed by the scientists for the measuring technique. The team is currently working to incorporate the technology into a device that can be used in real-world scenarios.

This technology is low cost, making it suitable for use in developing countries as well. Moreover, it’s simple to use and can be operated even without laboratory training, for example by authorities or tourists,” Güntner stated. It is also suitable for quality control in distilleries.

Methanol is more than just an irritant in conjunction with alcoholic beverages; it is also a vital industrial chemical—and one that might soon play an even more crucial role: methanol is being tested as a potential future fuel, since vehicles can be driven with methanol fuel cells. So an additional application for the new technology could be as an alarm sensor to identify leaks in tanks.

The research was part of the University Medicine Zurich—Zurich Exhalomics flagship project.


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