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A breathalyzer capable of measuring the amount of THC in the breath

PHOTO: THE CANADIAN PRESS / DARRYL DYCK
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After the blood, the urine or the hair, it is with the breath of the consumer that we will detect the cannabis

A team has developed a breathalyzer capable of measuring the amount of tetrahydrocannabinol (THC) in the user's breath. The breathalyser was developed using carbon nanotubes, tiny 100 000 carbon tubes, which are smaller than a human hair. Nanotechnology sensors can detect THC at levels comparable to or better than those of mass spectrometry, which is considered the gold standard for THC detection.

As recreational legalization is becoming more prevalent throughout the United States, there is also concern about what it means for enforcement. Drunk Driving Laws. Unlike the breathalyzer breathalyzer used to detect the presence of alcohol, police have no device that can be used in the field to determine if a driver is under the influence of cannabis. New research from the University of Pittsburgh is about to change that.

A team Interdisciplinary Department of Chemistry and Swanson School of Engineering has developed a breathalyzer that measures the amount of tetrahydrocannabinol (THC), the psychoactive compound, in the breath of the consumer. Current methods of drug testing rely on blood, urine or hair samples and can not be done in the field. They also reveal that the user has recently inhaled the drug and not that he is currently under the influence of alcohol.

The ethylotest was developed using carbon nanotubes, tiny tubes of carbon 100 000 times smaller than a human hair. The molecule of THC, along with other molecules in the breath, binds to the surface of nanotubes and modifies their electrical properties. The speed at which the electric currents recover is then indicated if THC is present. Nanotechnology sensors can detect THC at levels comparable to or better than mass spectrometry, which is considered the gold standard for THC detection.

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Their research took place under the supervision and with the permission of the US Drug Enforcement Agency.

"The semiconducting carbon nanotubes we use were not available just a few years ago," says Sean Hwang, lead author of the research and doctoral candidate in chemistry at Pitt. We have used machine learning to "teach" the ETA to recognize the presence of THC as a function of the recovery time of electrical currents, even when there are other substances, such as alcohol, present in the breath .

Hwang works at the Star Lab, led by Alexander Star, PhD, a chemistry professor with a secondary appointment in bioengineering. The group partnered with Ervin Sejdic, PhD, an associate professor of electrical and computer engineering at the Swanson School of Engineering, to develop the prototype.

"The creation of a prototype that works in the field has been a crucial step in the application of this technology," says Dr. Sejdic. "It took an interdisciplinary team to turn this idea into a usable and vital device for road safety."

The team took three years to develop a portable model of the device that could be used in the field.

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Professors Alexander Star and Ervin Sedjic of Pitt present cannatest

The prototype looks like a breathalyzer for alcohol, with a plastic case, a prominent mouthpiece and a digital display. It was laboratory tested and found to be able to detect THC in a breath sample that also contained components such as carbon dioxide, water, ethanol, methanol, and acetone. The researchers will continue to test the prototype, but hope that it will soon be put into production and ready for use.

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In the legal states, you'll see road signs that say "If you're driving high safely," but there's been no reliable and convenient way to apply this, "says Dr. Star.

"There are debates in the legal community about THC levels that would equate to drinking and driving. The creation of such a device is an important first step to ensure a true THC screening ".

Although law enforcement agencies can rely on years of research to document impaired driving alcohol levels, there is little research on THC.

In a report presented to Congress in 2017, the National Highway Traffic Safety Administration acknowledged that it has limited research data on cannabis impaired drivers and the level at which impairment begins. Star said it will allow researchers to start working to determine when and at what level of THC the alteration begins.

It probably also depends on the rate of consumption and the size of the person. The presence of THC in the breath does not mean that the person can be weakened, "says Star. "We will try to measure this in future research.

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