In a "breakthrough", scientists have developed a rapid and highly sensitive fingerprint test that can detect whether someone has used cocaine within seconds.
The new non-invasive technique developed by researchers, including those from University of Surrey in the UK, can pick up traces of cocaine, even after the subjects have washed their hands.
"Our results show the technique was 99 per cent effective in detecting cocaine use among the patients," said Catia Costa, from University of Surrey.
The team used chromatography paper to take fingerprint sample as part of a technique known as paper spray mass spectrometry.
Researchers took fingerprints from a group of patients seeking treatment at drug rehabilitation centres, as well as a larger group not known to be drug users.
All of those taking part washed their hands before the test in a variety of ways, and then samples were collected on the prepared chromatography paper.
The fingerprint was developed using chemicals, so that the ridges of the fingerprint (and therefore the identity of the donor) could be established prior to analysis.
When someone takes cocaine, they excrete traces of benzoylecgonine and methylecgonine as they metabolise the drug, and these chemical indicators are present in fingerprint residue.
Importantly, the traces can still be detected even after hand washing, researchers said.
"This is a real breakthrough in our work to bring a real time, non-invasive drug-testing method to the market that will provide a definitive result in a matter of minutes - we are already working on a 30 second method," said Melanie Bailey from the University of Surrey.
The study was published in the journal Clinical Chemistry....