Analysis at Your Fingertips?

Drug testing usually involves the collection and storage of blood and urine. These are potential biohazards that need to be properly stored and transported, and in a forensic setting, a chain of custody must also be established. But what if drug testing were as easy as taking someone’s fingerprints?

Using paper-spray mass spectrometry, a team led by scientists from the University of Surrey, UK, has created a method for testing for drug use in fingerprints. “There are a few publications in the literature that report the detection of drugs of abuse in fingerprint samples. However, these methods rely on extensive sample preparation steps as well as lengthy analysis time. But our method is both quick and sensitive and can use samples that are not hazardous – and easier to collect than blood and urine”, says Catia Costa, first author of the study and a researcher at the University of Surrey’s Ion Beam Centre.

The fingerprint sample is collected on a piece of chromatography paper, then a solvent is added and a voltage applied (see Figure 1). This process extracts traces of cocaine and substances produced when cocaine is metabolized (benzoylecgonine and methylecgonine). Analysis of 239 fingerprints from patients at a drug rehabilitation center and a control group of people not known to be drug users yielded a 99 percent true positive rate, and a false positive rate of 2.5 percent – even when study participants had washed their hands with soap before having their prints taken (1). And since the ridges of the fingerprint are visually established as part of the procedure, the identity of the donor can be identified.

The technique is adaptable to other substances that might be of interest in a medical or legal setting, such as prescription drugs, and explosives. The team now plan to look into commercializing the test, and assessing which fields would find it most valuable – as well as continuing to work on bringing analysis time down, with the ultimate aim of creating a 30-second method.