An infrared laser ablation coupled to a vacuum capture system, was employed by researchers from the Louisiana State University Department of Chemistry (LA, USA), that could be used in fingermark sampling. The results of the study have been published in the Journal of The American Society of Mass Spectrometry.
The approach works by focusing a highly-selective laser system, using mirrors and optical fibers, onto a surface containing a fingermark. After the laser lifts the fingermark, a vacuum pump system pulls the associated molecules into filter that captures everything left behind in a fingerprint. The contents of the filter can subsequently be analyzed in devices such as mass spectrometers to determine their mass, allowing their identification.
The team demonstrated that infrared laser ablation coupled to vacuum capture could be used to collect material from fingermarks deposited on different surfaces. Ablation and capture of standards from fingermarks were demonstrated on glass, plastic, aluminum and cardboard surfaces.
Matrix assisted laser desorption ionization was utilized to detect caffeine after spiking with amounts as low as 1 ng, as well as detection of antibacterial peptides from an antiseptic cream and condom lubricants. GC–MS was used to show detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface.
The research team will continue to work on generating optical fiber attachments for the laser system that could potentially aid the creation of a portable laser fingermark-capturing system to sample surfaces on the scene.
Sources: Donnarumma F, Camp E.E, Cao F, Murray K.K. Infrared laser ablation with vacuum capture for fingermark sampling. J. Am. Soc. Mass Spectrom. doi:10.1007/s13361-017-1703-2 (2017) (Epub ahead of print); https://phys.org/news/2017-06-guesswork-forensic-analysis-fingermarks.html