Direct detection of nicotine and cotinine in dusted latent fingermarks of smokers by using hydrophobic silica particles and MS

Sub-micron sized hydrophobic silica particles doped with carbon black have been employed with latent fingermarks on glass and metal surfaces to develop a simple method for detecting nicotine and cotinine using surface assisted laser desorption/ionisation-time of flight-mass spectrometry (SALDI-TOF-MS) in positive ion reflectron mode. Dusting of surfaces enables location of marks for conventional identification of details but the particles also act as a laser desorption/ionisation enhancing agent (LDI) equivalent to a standard matrix enhancer 2,5-dihydroxybenzoic acid used in matrix assisted LDI-TOF-MS (MALDI-TOF-MS). The method has been applied in the analysis of smokers' latent fingermarks on metal and glass surfaces. The metal surfaces were analysed following direct MS analysis of the pre-dusted prints, while the glass surfaces were analysed following lifting using commercial tape, and then MS analysis of these pre-dusted prints. In all cases of smokers, a major peak at m/z 163 (nicotine+1) and a less intense peak at m/z 161 (possibly anatabine+1) were found in the prints and in some cases additional peaks at 177 (cotinine+1) and 199 (possibly cotinine+Na) were observed. The presence of nicotine and cotinine in smokers' marks was confirmed using SALDI-TOF-MS-MS following high energy collision-induced dissociation when characteristic fragmentation patterns were observed for each compound. Copyright (C) 2009 John Wiley & Sons, Ltd.