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Saturday, 8 February 2020

Now Fingerprint will help in finding out if someone has handled or ingested cocaine


In many countries, the use of hard drugs such as cocaine is illegal and punishable by law. When authorities suspect cocaine use, blood tests are the norm. However, these tests require time and a complex supply chain before obtaining the first results. Recently, a team of researchers has developed a device capable of distinguishing, on the basis of a fingerprint, whether the person concerned has ingested or simply handled cocaine, all in less than two minutes.



A single fingerprint can discriminate if someone has recently touched or actually ingested cocaine. This test can be done in less than 2 minutes, much faster than blood tests, and could be used for forensic investigations or drug testing. The study was published in the journal Scientific Reports.



Melanie Bailey of the University of Surrey in the United Kingdom and her colleagues have developed a technique that detects traces of cocaine, as well as signs of cocaine use, on human skin. In addition to cocaine, the test detects a molecule called benzoylecgonine, which is excreted through the skin after a person has ingested cocaine. The chemical is also present as an impurity in some samples of cocaine sold on the street.

Mass spectrometry to detect traces of benzoylecgonine

But a person who has ingested cocaine will continue to excrete the molecule through sweat, so even after washing their hands, it is detectable in a fingerprint.

Bailey and his team took fingerprints of people who had touched 99% purity cocaine samples as well as much less pure street samples. They took the fingerprints immediately after handling the medication and again after the participants washed their hands.

Diagram of the mass spectrometry (MS) detection process. Credits: M. Jang et al. 2020

They also took the fingerprints of 26 people at a drug addiction clinic, who said they had used cocaine in the past 24 hours. For the test, the individual presses his finger on a piece of specialized paper for 10 seconds. The paper is then analyzed using a technique called mass spectrometry, to detect the presence of cocaine or benzoylecgonine.

Accurate, fast and reliable detection

In the 86 samples, the fingerprinting technique was 95% accurate. The team found that detection was possible up to 48 hours after contact or ingestion. Unlike blood tests, which are the current standard for testing cocaine use, fingerprint analysis can be done in less than 2 minutes.

(Top): Results of cocaine detection in the fingerprint of three volunteers (D1, D2, D3) at different times during 48 hours after touching 2 mg of 99% pure cocaine (A). And at different times for 12 days after touching 0.5 mg and 2 mg of 99% pure cocaine, respectively (B). (Bottom): Results of cocaine detection in the fingerprints of three volunteers (D1, D2, D3) at different times after washing their hands, after touching 0.5 mg (A) and 2 mg (B) 99% pure cocaine. Credits: M. Jang et al. 2020


The technique is now commercially available and could be used for drug testing. It could also be used in the future as a forensic tool to determine the presence of cocaine in fingerprints left at a crime scene, although the method may require further validation by then, explains David Berry, independent toxicology consultant in the UK.




Bibliography:

On the relevance of cocaine detection in a fingerprint

M. Jang, C. Costa, J. Bunch, B. Gibson, M. Ismail, V. Palitsin, R. Webb, M. Hudson & M. J. Bailey

Scientific Reports

volume 10, Article number: 1974 (2020)

https://doi.org/10.1038/s41598-020-58856-0

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