Gel-lifted fingerprints tested for drugs in forensics breakthrough

Forensic gel allows fingerprints to be viewed against a clear background, improving visualisation of the print. It has long been assumed that the gel carrier may also contain traces of other forensic material such as drugs or even DNA. However, existing techniques have not been able to distinguish between the chemicals in the gel and additional chemicals that could be forensic evidence.

Testing for the presence of the sleeping pill Zolpidem, the Loughborough team employed a technique called sfPESI-MS that used a rapid separation mechanism to distinguish the drug substance from the background of the gel.

The process involves sampling the chemicals from the gel lifters into tiny liquid droplets. Chemicals extracted into the droplets are then ionized, with drug substance chemicals more surface active than the gel chemicals, enabling them to be separated from the mixture. The presence of particular drugs can then be confirmed using mass spectrometry. The research is published in the journal Drug Testing and Analysis.