“Oh, my God,” gasped Dr Catia Costa. She was looking at the results of my fingerprint drugs test, which she helped pioneer as a researcher at the University of Surrey’s Chemistry Department. “It can’t be.”

“What is this showing?” I asked. “Cocaine. A lot of cocaine,” she replied. At that point, I had to come clean: I haven’t taken coke for a long time (it just makes me anxious), but I had rubbed some on my fingers that morning before I headed to the lab. Costa looked relieved.

Costa and her colleagues at Surrey have discovered that a way to test for cocaine use through a simple fingerprint. As detailed in their recent study, published in Scientific Reports, they were able to even distinguish between a person who had merely touched cocaine (like me) or someone who had actually taken it. Their findings could have far-reaching implications – not just for casual users sweating over their workplace drugs test, but for the whole field of forensic science and police investigation.

If I’m honest, I wasn’t sure that Costa’s machine could pick up any of the coke on my hands. I’d washed them three times with soap, touched a multitude of surfaces and allowed three hours to elapse before taking the test. But it picked it up straight away.

The author getting tested.

Just to be sure, I brought along a volunteer who shall remain nameless, but had consumed three lines of coke between 10PM and midnight the previous evening. The test revealed this just a few minutes after his prints were taken. “Good party?” Dr Melanie Bailey, another researcher on the project, laughed.

The method Bailey and Costa use is known as mass spectrometry – an analytical technique that measures the mass-to-charge ratio of ions. As part of their research, the researchers took fingerprints from volunteers who had touched samples of 99 percent pure coke and street samples that were adulterated – both immediately after they had touched the drug and after they had washed their hands. These results were compared against the fingerprints from 26 volunteers from a drug rehab clinic who had taken coke in the past 24 hours.

Out of the 86 samples taken, the testing was found to be 95 percent accurate. It’s quick: you press your finger against some specialised paper for ten seconds. Once that’s placed into the mass spectrometer, it takes a couple of minutes to get the results. But according to Bailey and her team, speed isn’t its main advantage.

“I suspect that someone carrying out workplace testing would want to know whether or not someone is under the influence of a substance or they had touched it,” she explained. “If they’ve touched it, there isn’t going to be any impairment. But if they’ve taken it, they are potentially going to be impaired. The aim is to distinguish between someone who has perhaps been in a certain environment and people that shouldn’t be driving a bus or an aeroplane or whatever.”

Fingerprint-wise, the difference between someone who has gotten on it the night before and someone who’s rubbed coke on his finger is a compound called benzoylecgonine. “If someone has taken or touched cocaine you’ll see two different molecules,” Bailey explained. “One is cocaine, the parent molecule, and one is the metabolite, benzoylecgonine.” Your body produces benzoylecgonine when you’ve had a line but not if you’ve just touched a banknote (studies have shown that a significant number of the banknotes in circulation contain traces of cocaine) or gone within a mile of a nightclub toilet.

But your fingerprint is, like your DNA, one of the most personal pieces of data that you’ll ever possess. Will testing people for drugs in this way lead to some potentially pretty negative consequences for our civil liberties?

“It very much depends on how it is used,” Bailey argued. “If you use a fingerprint for drug testing in the way that drug testing has always been carried out, that’s one thing. If using a fingerprint opens up new possibilities – which is what you are implying, you’ll have the ability to test more people and therefore you get a lot more information about people – then, yeah, maybe that would be controversial. It probably does open up ethical issues which would need to be considered.”

“But simultaneously, when you take blood or urine you’ve got DNA, which is more personal,” Costa added.

How far are we likely to be away from this tech being widely used? “I think it depends on investment. If any of your readers would like to sling us a few million pounds we’ll happily make a test very quickly,” Bailey laughed, taking a sip of her coffee. “We have a student who’s working as a fingerprint expert with Thames Valley Police and doing her PhD with us. She’s using mass spectrometry to look at developing better fingerprints and increasing the amount of information you can get from a fingerprint.”