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A variety of lighter fuel samples from different manufacturers (both unevaporated and evaporated) were analyzed using conventional gas chromatography-mass spectrometry (GC-MS) analysis. In total 51 characteristic peaks were selected as variables and subjected to data preprocessing prior to subsequent analysis using unsupervised chemometric analysis (PCA and HCA) and a SOFM artificial neural network. The results obtained revealed that SOFM acted as a powerful means of evaluating and linking degraded ignitable liquid sample data to their parent unevaporated liquids.

This study investigates the optimisation of peroxidase based enhancement techniques for footwear impressions made in blood on various fabric surfaces. Four different haem reagents: leuco crystal violet (LCV), leuco malachite green (LMG), fluorescein and luminol were used to enhance the blood contaminated impressions. The enhancement techniques in this study were used successfully to enhance the impressions in blood on light coloured surfaces, however, only fluorescent and/or chemiluminescent techniques allowed visualisation on dark coloured fabrics, denim and leather. Luminol was the only technique to enhance footwear impressions made in blood on all the fabrics investigated in this study.

ABSTRACT:Toxicology studies are typically performed on single compounds, which we hypothesized would miss adverse synergies from chemical mixtures. This hypothesis was tested using an insect repellant and sunscreens because both groups include known permeation enhancers, with prior pediatric reports of toxicity from highly concentrated DEET (N,N-diethyl-m-toluamide). Using real-time mass spectroscopy in a hairless mouse skin model, we confirmed substantial penetration of a 20% DEET standard. Despite a lower (10%) DEET content, a commercially marketed sunscreen formulation had a 6-fold more rapid detection (5 versus 30 min) and 3.4-fold greater penetration at steady state. We also tested the efficacy of DEET microemulsion products and confirmed that one successfully slowed the onset of absorption, but not the steadystate permeation. Risks from mixtures of potential toxins are worthy of routine testing, which can be accomplished by simple assays, and are of utmost importance for pediatric applications.Toxicology studies are fundamental to our approach for using an enormous variety of environmental, industrial, and medicinal compounds, which are of particular importance to the pediatric population. We were concerned that mixtures of chemicals might unintentionally enhance toxicity, and chose to study a topical insect repellant in this regard. The routine use of N,N-diethyl-m-toluamide (DEET) has been widely advocated by the medical community and media after recent illnesses from West Nile encephalitis and other infectious agents. Despite DEET's efficacy and superb safety record, we believe it is imperative that this and other topical agents not be used in commercial mixtures that unintentionally enhance their transdermal absorption. This raises a much wider and more important concern that serious adverse interactions between common potential intoxicants may be underappreciated because typical industry testing does not include that of mixtures. Some sunscreens and even DEET itself have been described as permeation enhancers (Windheuser et al., 1982;Benson, 2000;Hayden et al., 1997), and awareness of problematic formulations would be of value to the public, children in particular. Especially with case reports and media stories of alleged pediatric behavioral or neurotoxicity, there has been a longstanding concern that transdermal absorption of high-concentration products might pose a health risk (Robbins and Cherniack, 1986;Selim et al., 1995;Briassoulis et al., 2001).We hypothesized that some topical formulations might influence their component's permeation, but could not be detected by prior steady-state models utilizing single agents. We used a mouse skin model and liquid chromatography/mass spectrometry to quantify realtime absorption kinetics of DEET in various concentrations and in a commercial sunscreen product. Materials and MethodsA flow-through cell was devised that would permit mounting of 1.27-cm 2 full-thickness hairless mouse skin and allow quantification of transdermal penetration into a small-volume w...

Most footwear marks made in blood on a surface such as fabric tend to be enhanced in situ rather than physically recovered using a lifting technique prior to enhancement. This work reports on the use of an alginate material to recover the impressed footwear marks made in blood and deposited on a range of fabric types and colours. The lifted marks were then enhanced using acid black 1 and leuco crystal violet with excellent results. This presents a new method for the lifting and recovery of blood impressions in situ from crime scene followed by subsequent mark enhancement of the lifted impression.

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