British chemists have found that fingerprint analysis gives traces of cocaine and its metabolite, even if the person is not used, and only touched the substance. To do this, they are using mass spectrometry analyzed the fingerprints of several people who either used cocaine or touched him: in the sweat of those and the other test gave traces of the substance. After washing your hands, however, traces of metabolites of cocaine benzoylecgonine were found only in the fingerprints of those who took the drug. Article published in the journal Scientific Reports.
Classically, drug tests are carried out using the analysis of biological fluids of humans: depending on the substance and its traces (or traces of its metabolites) can be detected in blood, saliva or urine for hours, days or even weeks. For example, cocaine in urine can be detected within 6-8 hours, and its main metabolite , benzoylecgonine — and in a few days.
The methods used in the tests for drugs are fairly accurate and effective, but still require the sampling of biological material that may complicate the procedure. An alternative method to detect substances — analysis of sweat, for example, through fingerprints, as in any other biological fluid, sweat can contain traces of the substance and its metabolites. This method in 2015 was developed and successfully tested a group of British chemists under the leadership of Melanie Bailey (Melanie Bailey) from Guildford University.
In the new work, they decided to check whether you can use the same method to detect contact with the substance. They asked 28 volunteers who do not use cocaine, touch samples of the two substances from cocaine 99 percent and 41 percent. After that, they took fingerprints: before that, the parties will either wash their hands with soap or not, and for 10 minutes put on gloves so that your palms sweaty. On paper with fingerprints then added to the solution of acetonitrile with water to evaluate traces of the substance using mass spectrometry.
To hand wash the traces of pure cocaine found on the fingerprints of the seven participants, and the traces of the metabolite benzoylecgonine — two participants, but after washing your hands, no trace could be detected. After contact with the substance containing 41% of cocaine, traces of the substance and the metabolite found at the three people. It is interesting that traces of cocaine were present in the fingerprints of people even after some time — up to 48 hours after exposure to cocaine: in this case, the researchers did not control the number of times participants washed their hands.
After that they fingerprinted in 26 patients rehab: all of them took cocaine two days before the study. Traces of cocaine and its metabolites were detected in the fingerprints of all patients as before they washed his hands and after.
Scientists came to the conclusion that the result of a drug test using fingerprints can be positive even if the person just touched the substance and not use it. On the other hand, washing your hands before the test helps to distinguish those who had taken cocaine, from those who simply had contact with him: traces of benzoylecgonine after washing your hands, for fingerprints remain only in the case if the drug was adopted.
Perhaps the most unusual method of studying the consumption of drugs used in 2016, Australian scientists. For four years they analyzed wastewater Adelaide and found, for example, that during this period increased by half the consumption of methamphetamine.