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

Abstract

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/ionisationtime 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.

Environmental nicotine contamination in latent fingermarks from smoker contacts and passive smoking

“…Thus the MS of the five non-smoker's fingermark transfers show m/z 163 values which are not significantly higher than m/z 163 peak values in the MS of uncontaminated nonsmoker's marks. The identity of the m/z 163 signal from smokers' fingermarks was confirmed as nicotine from its SALDI-TOF-MS-MS (CID) fragmentation pattern, in line with our reported observations [12]. We have previously shown that cotinine (FW 176), which is the major metabolite of nicotine, can be detected in the dusted latent fingermarks of a small number of smokers [12] and our transfer experiments indicate that we can also detect cotinine together with nicotine in the fingermarks of non-smokers after shaking hands with a smoker (spectra not shown).…”

“…To prove the identity of m/z 163, SALDI-TOF-MS-MS (using CID) was carried out and the resulting fragmentation pattern was compared with the corresponding pattern at m/z 163 from a nicotine standard solution. Both spectra were performed under identical conditions and as we have reported for the m/z 163 peak in smokers, produced identical patterns using the hydrophobic silica particles proving that nicotine is in the sample of extract [12].…”

“…The process takes no more than 15 min to complete. We have also previously reported that this technique can be used to reliably distinguish smokers from nonsmokers, based on the intensity of m/z 163 peak ([nicotine+H] + molecular ion) in the SALDI-MS spectrum [12].…”

“Total IBA” – Where are we?

“…This allows the analysis of organic features of large, delicate and valuable (such as paintings or manuscripts), or wet biological samples [115] , without the need for subsampling. Secondary ion mass spectrometers are already available for work in air, in MALDI (matrix-assisted laser desorption ionization [116]) and DESI (desorption electrospray ionisation [117]) applications, neither of which have the possibility of the simultaneous complementary techniques giving quantification and depth sensitivity.…”

Functionalized Nanoparticles and Nanostructured Surfaces for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

“…Recently, hydrophobic silica particles doped with carbon black have been employed for the analysis of latent fingermarks on glass and metal surfaces in order to develop a simple method for detecting nicotine and cotinine. 91 Watanabe et al have developed SALDI-MS using zinc oxide (ZnO) NPs with anisotropic shapes. 92 ZnO-SALDI is advantageous for post-source decay (PSD) analysis and produces a simple mass spectrum in the case of phospholipids.…”