Tiny trace amounts of cocaine, methamphetamine, and heroin can be found on fingerprints using mass spectrometry, according to a new study.

The advanced technique can find incredibly small amounts of the narcotics on a fingerprint, the National Institute of Standards and Technology researchers found.

Amounts as small as 10 picograms were detected – a level which is equivalent to the weight of a human cell, according to online references.

The fingerprints, if left on silicon, showed accurate levels and concentrations of all three substances, concluded the study, published April 27 in the journal Analytical Chemistry.

On paper, the fingerprints showed cocaine clearly – but meth and heroin were harder to identify, due to limitations in the medium, they concluded.

Shin Muramoto, the lead author of the report, said by email that the experiments are not useful in a conclusive criminal investigation – yet.

“What makes this challenging is the huge variability in the amount of drugs that are present in the everyday objects we touch,” Muramoto said. “Currency such as a twenty-dollar bill is known to contain heroin, but the amount varies enormously between bill to bill. Just because a person touched the bill with a high heroin loading does not make him a habitual user.”

The next step, Muramoto said, is to detect drug metabolites – the byproducts left after use of a drug – on the fingerprints.

Fingerprints have been targeted as a potential source for investigative information over the last decade.

The British-based company Intelligent Fingerprinting currently markets a mobile drug-screening device, which apparently works of miniscule samples of sweat.

Previous studies have tried detecting trace amounts of drugs in latent fingerprints using Raman spectroscopy, a different kind of evaluation.