Copy toner samples were analyzed using scanning electron microscopy with X-ray dispersive analysis (SEM-EDX) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). Principal component and cluster analysis of SEM data for 166 copy toner samples established 13 statistically different subgroups, with the presence or absence of a ferrite base being a major division. When toners were compared for which both SEM and reflection-absorption infrared spectral data were available, 41% of the samples could be assigned to specific manufacturers. Py-GC/MS on poly(styrene:acrylate)-based toners produced eight peaks relevant to toner differentiation. One third of the toners clustered in a small group that contained five statistically different subgroups. Of the 57 toners for which both Py-GC/MS and SEM data were available, 31 could be differentiated using the combined analytical results. The synergy of the complementary information provided by Py-GC/MS and SEM narrows matching possibilities for forensic investigations involving copied or laser printed documents.
A senior-level undergraduate laboratory experiment that demonstrates the use of solid-phase microextraction (SPME) and capillary gas chromatography-mass spectrometry (GC-MS) was developed for the identification of volatile compounds in consumer products. SPME minimizes sample preparation and concentrates volatile analytes in a solvent-free manner.
Supercritical fluid extraction (SFE) using CO2 modified with methanol (10%) was employed for the extraction of cocaine from human hair. Extraction conditions were developed by using designed experiments to characterize the effects of pressure, temperature, and percent methanol on the recovery of cocaine from hair. When compared to the conventional acid hydrolysis method for hair analysis, SFE was faster and gave higher recoveries. Amounts of cocaine, benzoylecgonine (cocaine metabolite), codeine, and morphine in a hair standard reference material were determined by SFE-gas chromatography/ mass spectrometry (GC/MS) and found to be in agreement with reported levels. Analyses of hair from forensic case studies are also reported.
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