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Detecting marijuana

Woman taking a breathalyzer test

Combining organic chemistry and electrochemistry could lead to a marijuana breathalyzer. 

14th May 2020

Muriel Cozier

With some US states, and countries, decriminalising the use of marijuana, the need to easily detect when an individual might be under the influence of the drug while, for example, driving has become important.  Research indicates that 14 million people in the US smoke marijuana and drive.

Researchers from the University of California, US have developed what they describe as a simple method, similar to that used in an alcohol breathalyser, for detecting the presence of marijuana. The research has been published in the journal Organic Letters.

The process involves the oxidation of delta-9-tetrahydrocannabinol (THC). The researchers say that removal of a hydrogen molecule leads to changes in the compound’s colour that can be detected. Having found a number of routes that lead to the oxidation of THC, the research team settled on putting electricity into the THC to produce the chemical changes they were looking for.  

‘Doing organic chemistry using electrochemistry is not something that people in my field historically have done regularly,’ said senior author of the paper Neil Garg, the Kenneth N. Trueblood Professor of Chemistry and Biochemistry and chair of UCLA’s department of chemistry and biochemistry.

The team of chemists say that the next step is to achieve the same results with a breath sample from person who has recently consumed marijuana, and to avoid false positives. Studies suggest that marijuana on the breath can reliably reveal if the chemical was smoked or otherwise consumed in the last four to five hours, the team said.

While the research team have developed the chemistry for the breathalyser, a device has yet to be created. Evan Darzi, lead author of the paper and a former postdoctoral scholar at UCLA’s department of chemistry and biochemistry said ‘We want a simple breathalyzer that doesn’t require specialist training…’ The hope is the breathalyzer would be inexpensive enough for consumers to buy so that they can test themselves before deciding whether to drive.

The researchers noted that in order to carry out their work they had to obtain a licence from the US Drug Enforcement Administration to study THC in their laboratory. They added that there were still significant challenges in developing their technology at university due to federal regulations. UCLA has filed for a provisional patent application on the THC oxidation.

Organic Letters DOI:10.1021/acs.orglett.0c01241

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