No abstract

Thumbs up: A method of fingerprinting that enables both identification of an individual and simultaneous determination of the chemical makeup of the sweat deposited in the fingerprint has been determined. Potential applications of this methodology are enormous as the functionalization of nanoparticles with other antibodies enables the specific detection of numerous antigens within a fingerprint.

An investigation was carried out to identify oxidation products of squalene (SQ) in latent fingerprints. Oxidation products of SQ incubated in solution with Rose Bengal as a photooxidizer were isolated by semipreparative HPLC-UV and identified by direct infusion ESI-MS and flow injection APCI-MS. Squalene hydroperoxides ranging from squalene monohydroperoxide (SQ-[OOH]) to SQ-[OOH]5 were identified together with SQ epoxide. SQ-[OOH] was the main oxidation product. An LC/APCI-MS method was developed and used to monitor the fate of SQ in solution and in latent fingerprints and the formation of SQ-[OOH] and SQ epoxide. SQ-[OOH] and SQ epoxide were detected in freshly deposited prints but increased markedly after 1 day and continued to increase up to 5 days after print deposition. By day 7, these substances could no longer be detected in prints. SQ was rapidly depleted from prints such that by day 7 it was no longer detected. A similar pattern was seen for SQ stored in the light in dichloromethane but with a slower formation of SQ-[OOH] and SQ epoxide. The oxidation of SQ in solution in the presence and absence of photooxidizer was shown by TLC to proceed as follows: SQ-->SQ-[OOH]+SQ epoxide. SQ-[OOH]-->SQ-[OOH]2-->SQ-[OOH]3-->SQ-[OOH]4+SQ-[OOH]5, with oxidation being more rapid in the presence of photooxidizer. SQ-[OOH]4 and SQ-[OOH]5 could still be detected at 20 days in a solution of SQ aged in solution in the absence of photooxidizer. The oxidation products of SQ should make suitable targets for development of new reagents for visualizing latent fingerprints in forensic science.

Magnetic particles functionalised with anti-cotinine antibody have been used to image latent fingermarks through the detection of the cotinine antigen in the sweat deposited within the fingerprints of smokers. The antibody–magnetic particle conjugates are readily applied to latent fingerprints while excess reagents are removed through the use of a magnetic wand. The results have shown that drug metabolites, such as cotinine, can be detected and used to image the fingermark to establish the identity of an individual within 15 minutes

In situ attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopic imaging has been used to obtain chemical images of fingerprints under controlled humidity and temperature. The distribution of lipid and amino acid components in the fingerprints from different donors left on the surface of the ZnSe crystal has been studied using an in situ FT-IR spectroscopic imaging approach under a controlled environment and studied as a function of time. Univariate and multivariate analyses were employed to analyze the spectroscopic dataset. Changes in the spectra of lipids with temperature and time have been detected. This information is needed to understand aging of the fingerprints. The ATR-FT-IR spectroscopic imaging offers a new and complementary means for studying the chemistry of fingerprints that are left pristine for further analysis. This study demonstrates the potential for visualizing the chemical changes of fingerprints for forensic applications by spectroscopic imaging.