Researchers create breathalyzer that can detect marijuana

Pitt researchers create breathalyzer that can detect marijuana
Ervin Sejdic, PhD (left) and Alexander Star, PhD, hold up the prototype of their THC-detecting device. Credit: University of Pittsburgh

As recreational marijuana legalization becomes more widespread throughout the U.S., so has concern about what that means for enforcing DUI laws. Unlike a breathalyzer used to detect alcohol, police do not have a device that can be used in the field to determine if a driver is under the influence of marijuana. New research from the University of Pittsburgh is poised to change that.

An interdisciplinary team from the Department of Chemistry and the Swanson School of Engineering has developed a breathalyzer device that can measure the amount of tetrahydrocannabinol (THC), the psychoactive compound in , in the user's breath. Current drug testing methods rely on blood, urine or hair samples and therefore cannot be done in the field. They also only reveal that the user has recently inhaled the drug, not that they are currently under the influence.

The breathalyzer was developed using carbon nanotubes, tiny tubes of carbon 100,000 times smaller than a human hair. The THC molecule, along with other molecules in the breath, bind to the surface of the nanotubes and change their . The speed at which the electrical currents recover then signals whether 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.

"The semiconductor carbon nanotubes that we are using weren't available even a few years ago," says Sean Hwang, lead author on the paper and a doctoral candidate in chemistry at Pitt. "We used machine learning to 'teach' the breathalyzer to recognize the presence of THC based on the electrical currents' recovery time, even when there are other substances, like alcohol, present in the breath."

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

"Creating a prototype that would work in the field was a crucial step in making this technology applicable," says Dr. Sejdic. "It took a cross-disciplinary team to turn this idea into a usable device that's vital for keeping the roads safe."

The prototype looks similar to a for alcohol, with a plastic casing, protruding mouthpiece, and digital display. It was tested in the lab and was shown to be able to detect the THC in a breath sample that also contained components like carbon dioxide, water, ethanol, methanol, and acetone. The researchers will continue to test the prototype but hope it will soon move to manufacturing and be available for use.

"In legal states, you'll see road signs that say 'Drive High, Get a DUI,' but there has not been a reliable and practical way to enforce that," says Dr. Star. "There are debates in the legal community about what levels of THC would amount to a DUI, but creating such a device is an important first step toward making sure people don't partake and drive."

The paper detailing this research, "Tetrahydrocannabinol (THC) Detection using Semiconductor-enriched Single-Walled Carbon Nanotube Chemiresistors," was published in the journal ACS Sensors.


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More information: Sean I. Hwang et al, Tetrahydrocannabinol Detection Using Semiconductor-Enriched Single-Walled Carbon Nanotube Chemiresistors, ACS Sensors (2019). DOI: 10.1021/acssensors.9b00762
Journal information: ACS Sensors

Citation: Researchers create breathalyzer that can detect marijuana (2019, August 27) retrieved 17 September 2019 from https://phys.org/news/2019-08-breathalyzer-marijuana.html
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Aug 27, 2019
When are we getting a tool that detects if the driver was sleepy? Hopped up on opiates?

You know, things that actually cause measurable amounts of deaths and accidents alongside alcohol use in driving?

But by all means, invest in finding out if someone has thc in their system. it's sooooo dangerous. I could save you tons of money and time. You just camp out around any fast food place or convenience store or diner after 9pm and arrest everyone buying food. You'll have a higher success rate of getting drunk / high / sleepy etc drivers and 0 need for R&D on single-task devices.

mqr
Aug 27, 2019
What a great invention! just what the world needs, with the countless lives lost to cannabis.... wait....

Where is the detector of racism? the detector of misogyny? homophobia detector? detecting if a man likes child porn? we can build those detectors, but yes, the essence of Western civilization would be "damaged"

Aug 27, 2019
Apparently we have a least a few potheads reading, and commenting, on Phys.org...

Aug 27, 2019
Does this only detect THC if it was inhaled (smoked, vaped) or can it detect it if it was ingested?

Aug 27, 2019
pretty sure there was a story recently about the difficulty in measuring thc concentrations when added to chocolate ...so I imagine ingesting thc (being that it's not a volatile liquid like alcohol) can be very difficult. Especially since it's broken down into a different compound than what you get when you breathe it in.

Not a pothead. Just tired of the hypocritical at best and almost definitely racist source of how weed has been treated in the US in relation to all of the other drugs (both legal and illegal). And the stupidity of "standardized" drug tests in general. As if any drug has the same effect on someone given the same amount, even less so the psychoactive variety.

Aug 27, 2019
No, no, nooooooooo!
Say it ain't so.

Aug 27, 2019
Well - it had to happen. IMOE although its nothing like the impediment alcohol is, with pot there can be moments of inattention, and as a responsible member of society I cannot object. We should persue sobriety, and not make concessions for our persuit of intoxication when in positions of responsibilty. (Slow clap). Funny that the developers look like real heads.

Aug 28, 2019
Show it works after imbibing chocolate milk or Ibuprofen. Otherwise it won't be admissible in court.

Aug 28, 2019
Show it works after imbibing chocolate milk or Ibuprofen. Otherwise it won't be admissible in court.

It doesn't need to be 100 % accurate. I don't know how police use breathalyzers in the US but here they are just used as a quick check. If you blow anything near or over the legal limit, you will taken to more accurate blood sample tests. No one is prosecuted only based on breathalyzer tests.

I know the current THC-tests here give a lot of false positives but they are still used. The test can even so positive if you've smoked 2-3 days ago and there still can be traces in your blood too so it's very random. Hope they will find an improvement even though I don't consider driving slightly high dangerous.

Aug 28, 2019
The problem is the blood tests aren't accurate either.

So none of this is court-admissible evidence so far.

Aug 28, 2019
As recreational marijuana legalization becomes more widespread throughout the U.S., so has concern about what that means for enforcing DUI laws.
If you need a sophisticated scientific test to determine a driver is "under the influence" of marijuana, i.e., you can't make a legal determination that a person's ability to safely operate a motor vehicle is in some way physically impaired short of basing it on 50 years of war-on-drugs refer-madness propaganda, then case dismissed; what a waste of effort from two perfectly good PhDs.

Some figures from 2016:
Number of fatal opioid overdoses: 18,000
Number of alcohol related deaths: 300,000
Number of fatal marijuana overdoses in all of recorded history: Fucking Zero

Corruption at the top and a shit-ton of propaganda is the only explanation for the last 50 years of the failed "war on drugs" all at the tax payer's expense...

Aug 28, 2019
Look up Henry Ford, hemp, and William Randolph Hearst.

Aug 28, 2019
Look up Henry Ford, hemp, and William Randolph Hearst.
Oh yeah, and you forgot to mention the Rockefeller family with Standard Oil, and DuPont ... superior competitors, yay capitalism...

Aug 28, 2019
DuPont has been engaged in fascist activities for a very long time. Look up the Business Plot and General Smedley Butler.

Aug 28, 2019
Why not first do a study to compare the effects of driving under the influence of cannabis to the effects of driving under the influence of alcohol? Pretty sure you will find these are apples and oranges in terms of impairment. But hey, gottta make a buck, right?

Aug 28, 2019
DuPont has been engaged in fascist activities for a very long time. Look up the Business Plot and General Smedley Butler.
They could return everything they took from humanity and there's still not a yardarm high enough for just recompense of the uncountable millions of humans who died in all the wholly unnecessary wars of the last century. Bush's daddy Prescott was a card carrying nazi... anyone who's still a member of the republican party at this point is a conservative fascist, if not horribly under-informed.

KBK
Aug 28, 2019
Yet the dems were the party of slavery and the south.

The republican party was the party of Lincoln and the north. The party of emancipation.

Look to the people who are inside of it, the layers deep, the real power of the throne for each party.

It is possible to say it is an oligarchy game, for various factions, that is layers deep, and they just 'sign' (hand wave') to each other in the public aspects. It's a game of labels and cover stories.

So there is no such thing as parties, just controlled politics so that oligarchy, in it's various factions, remains unknown to the masses ----and in charge.

I'd say that there is probably not a single person alive today who has actually witnessed or lived in actual democracy at the given national level (in any country).

Show me the difference between communism and capitalism, I'm not seeing it.

One uses shekels more openly and in context than the other, but both exist as humanity crushing life destroying oligarchies.

Aug 28, 2019
Show me the difference between communism and capitalism, I'm not seeing it
Two sides of the same corrupting influence of monetarism. The love of money... in a truly competitive marketplace where cost is based on the reality of time and energy, the price of everything should decline as technology progresses and it should approach zero until someone finally implements a self-replicating machine for production, at which point the price becomes free ...

Aug 29, 2019
Pot smokers are just like tobacco smokers and their disgusting habits. Any excuse is ok to imbibe. Unlike responsible alcohol drinkers, the SOLE reason for cannabis is to get stoned. Pathetic way to live.

Aug 29, 2019
Pot smokers are just like tobacco smokers and their disgusting habits. Any excuse is ok to imbibe. Unlike responsible alcohol drinkers, the SOLE reason for cannabis is to get stoned. Pathetic way to live.

You're wrong. Some people smoke cannabis just for taste and go to trips just to taste different flavors around the world. Just like people who take something like beer or whiskey seriously.


Aug 29, 2019
CBP tested some guy's honey he was bringing back from Jamaica and claim the field test came out positive for meth. They got their noses pushed in; when detailed tests from the lab came back, no meth, it was honey. They held him for three months.

They offered him the honey back. He won't touch it. He's suing.

If I was his lawyer I'd get the honey, and use the exact test from the exact company that made it. Depending on the results, I'd sue one, the other, or both of CBP and the company that made the test.

https://www.cnn.c...dex.html

yep
Aug 30, 2019
Pot smokers are just like tobacco smokers and their disgusting habits. Any excuse is ok to imbibe. Unlike responsible alcohol drinkers, the SOLE reason for cannabis is to get stoned. Pathetic way to live.


Thousands of years of recorded history on cannabis and you spew culture war bulshit. Might want to look at your own shortcomings as "people see the world as they are not as it is"
After you are done with some self evaluation consider sparking one up it might help you become less of a c*nt.

Aug 30, 2019
Seriously, why all the hullabaloo, when this can be a useful tool to get a potential accident off the street until they are not.

/ Now, where did I rest that spliff.

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