Detection of drugs and their metabolites in dusted latent fingermarks by mass spectrometry

Abstract

A hydrophobic silica dusting agent containing carbon black has been used with latent finger marks to demonstrate that the agent can act as an enhancing matrix to generate a simple method for detecting a range of drugs using surface assisted laser desorption/ionisation time-of-flight mass spectrometry (SALDI-TOF-MS) in positive ion reflectron mode. The dusting agent produces developed marks for locating/visualising the prints whilst also acting as a SALDI-TOF-MS enhancer that is equivalent to the standard matrix enhancer 2,5-dihydroxybenzoic acid. This method has been applied to the analysis of latent fingermarks for contact residues on fingers, and for detection of illicit drugs for both parent drugs and their metabolites. Analysis was performed by direct MS analysis of the pre-dusted fingermarks on the surface of a target plate and, following lifting using commercial tape, MS analysis of the lifted marks. When 19 commercial powders were used only three produced MS spectra but with intensities less than those produced with the new powder. The presence of the parent drug and its metabolites was confirmed using SALDI-TOF-MS-MS following high energy collision induced dissociation when characteristic and unique fragmentation patterns were observed in each case. The distribution of these compounds on fingermarks was subsequently demonstrated using commercially available imaging software.

A competitive enzyme immunoassay for the quantitative detection of cocaine from banknotes and latent fingermarks

“…In addition, the use of SALDI-TOF-MS enabled the detection of EDDP, a major metabolite of methadone, together with its parent drug in the same fingermark from an individual taking methadone [16]. As methadone is taken as an oral dose, it was concluded that the presence of the parent drug in the fingermark arises from its secretion from the blood in the same manner as for metabolites.…”

“…In addition, Rowell et al were able to show isolated patches of cocaine contamination in a fingerprint obtained from an individual being treated at a drug addiction centre using surface assisted laser desorption/ionisation time-of-flight mass spectrometry (SALDI-TOF-MS). The non-homogenous pattern of cocaine contamination in the print was thought to be due to the subject's fingertip coming into contact with the drug prior to the time of sampling [16]. Analytical methods for the detection of these types of cocaine residues in latent fingermarks could be used in a forensic context, as their presence would provide further evidence of a suspect's involvement in drug use or trade.…”

“…Additional information in a forensic context, such as the use by or recent exposure of an individual to illicit drugs, could provide enhanced evidence between a fingermark and a suspect. The successful detection of cocaine and other drug compounds in latent fingermarks is known using a number of different analytical approaches, and is particularly well-described for prints artificially doped with the compound of interest [14][15][16][17].…”

“…The immunodetection of cocaine on banknotes is limited to the application of strip-based immunoassays originally developed for qualitative detection of the drug in urine [24,25]. The detection of cocaine extracted from doped fingerprints is similarly focused on MS-based approaches, such as desorption electrospray ionization (DESI)-MS [15] and SALDI-TOF-MS [16] or Raman spectroscopy [14,17].…”

Development of Laser Desorption Imaging Mass Spectrometry Methods to Investigate the Molecular Composition of Latent Fingermarks

“…As an exemple, desorption electrospray ionization (DESI) MS has been successfully applied to several exogenous substances and external uptake detection [17]. Surface assistedlaser desorption/ionization-time-of-flight (SALDI-TOF) MS has been carried out for the detection of some fatty acids, dehydrated cholesterol, squalene, as well as the identification of explosives, drugs, and nicotine residues [8,18,19]. More recently, matrix-assisted-laser desorption/ionization (MALDI) TOF MS has been reported for the detection of endogenous substances, such as amino acids, fatty acids, peptides, dehydrated cholesterol, squalene, DAGs, and TAGs, as well as surfactants, polymers, drugs, pharmaceuticals, and explosives [20][21][22].…”