A Novel Test Sample for the Quantification of Illicit Drugs in Fingerprints using Imaging Mass Spectrometry
Shinichiro Muramoto, Thomas Forbes, Arian C. van Asten, John Gillen
A novel standard for the forensic analysis of fingerprints was introduced and characterized using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and desorption electrospray ionization mass spectrometry (DESI-MS), aimed at the trace level detection and quantitative analysis of drug molecules embedded in a latent fingerprint. A calibration array containing roughly (1, 5, 10, 25, and 50) ng of cocaine, methamphetamine, and heroin was deposited using a precision drop-on-demand inkjet printer onto fingerprints made of artificial sebum. Chemical analysis yielded peak intensities that were used to formulate a regression equation which was then successfully used to determine the surface concentration of drugs pre-mixed in an artificial sebum. For a pre-mixed sebum containing 250 µg of cocaine, for example, ToF-SIMS was able to determine that a fingerprint generated by pressing the analyte-laden plastic finger onto a fluorinated silicon substrate contained (137.8 ± 15.8) ng/mm2 of cocaine, corresponding to roughly 7% of the total cocaine molecules being transferred in one deposition. When the substrate was changed to a cotton paper, only (19.3 ± 7.4) ng/mm2 of cocaine was detected, corresponding to just 0.9% of transfer. The effect of substrate type on the attenuation of signal turned out to be quite severe for paper, as it is thought that the cocaine molecules were being absorbed into the substrate. This was consistent with the results for DESI, where the surface concentration of cocaine on paper was (270 ± 121) pg/mm2, or roughly 1.7% transfer.
, Forbes, T.
, van, A.
and Gillen, J.
A Novel Test Sample for the Quantification of Illicit Drugs in Fingerprints using Imaging Mass Spectrometry, Analytical Chemistry, [online], https://doi.org/10.1021/acs.analchem.5b01060
(Accessed June 30, 2022)