Browsing by Subject "Latent fingermarks"
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Item Monitoring compositional changes of the lipid fraction of fingermark residues deposited on paper during storage(Forensic Chemistry, 2016-11-01) Frick, A.A.; Chidlow, G.; Goodpaster, John V.; Lewis, S.W.; van Bronswijk, W.Characterising the changes in fingermark composition as a function of time is of great value for improving fingermark detection capabilities by understanding the processes and circumstances under which target compounds become degraded. In this study, gas chromatography-mass spectrometry was used to monitor relative changes in the lipids from latent fingermarks over 28 days. Principal component analysis of the relative composition of 15 lipids in fingermarks showed that fingermark age was a significant contributor to the variability observed in the data, but that inter-donor variability was also significant. This was attributed principally to changes in the relative amounts of squalene, which rapidly decreased in the fingermarks. It was also observed, however, that most fingermarks exhibited relatively small changes in composition during the first seven days, followed by more rapid changes up to 28 days. Significant inter-donor variation of both initial fingermark composition and the rates and nature of loss processes was observed, which was reflected in the relative projection of samples from different donors. Finally, samples stored with no exposure to light or airflow for 28 days were projected significantly closer to the samples analysed on the day of deposition than those exposed to light, due to the reduced photodegradation rate of squalene.Item Preparation, characterization, and application of a lipophilic coated exfoliated Egyptian blue for near-infrared luminescent latent fingermark detection(Forensic Chemistry, 2020-05-01) Shahbazi, Sorour; Goodpaster, John V.; Smith, Gregory D.; Becker, Thomas; Lewis, Simon W.A simple technique is described to create nanoscale near-infrared luminescent Egyptian blue pigment particles with lipophilic surfaces for latent fingermark detection. An exfoliated Egyptian blue powder coated with cetrimonium bromide was prepared using a simple, one-pot process. Particle size and surface coatings were characterized using scanning electron and atomic force microscopies, dynamic light scattering, and infrared and luminescence spectroscopies. This new fingermark dusting powder presents more contrast compared to uncoated Egyptian blue of comparable particle size as well as a commercial visible light fluorescent (Blitz Red) powder in the detection of aged fingermarks on model surfaces. The coated Egyptian blue pigment is a cost-effective fingermark dusting powder that reveals high contrast latent fingermarks with simple, inexpensive photography equipment.Item Studies into Exfoliation and Coating of Egyptian Blue for Application to the Detection of Latent Fingermarks(Chem Rxiv, 2020-09-23) Shahbazi, Sorour; Goodpaster, John V.; Smith, Gregory; Becker, Thomas; Lewis, Simon W.We have recently demonstrated that exfoliated Egyptian blue powder coated with cetrimonium bromide is effective for detecting latent fingermarks on a range of highly-patterned non-porous surfaces (see reference). In this extension of that work, we here present our preliminary studies into alternative approaches to preparing exfoliated Egyptian blue with a variety of different coatings. The various powders were then applied to the detection of latent fingermarks on non-porous surfaces. This proof of concept study demonstrated that there is potential improvement in performance compared to our previous work, however more comprehensive studies are required to compare the quality of the fingermarks developed with these powders against particles exfoliated in water.