title: Forensic discrimination of photocopy and printer toners. III. Multivariate statistics applied to scanning electron microscopy and pyrolysis gas chromatography/mass spectrometry.
abstract: 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.
authors.affiliation: Department of Chemistry and Biochemistry, The University of South Carolina, Columbia, SC 29208, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Egan
authors.forename: Randolph C
authors.initials: RC
authors.lastname: Galipo
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kochanowski
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Morgan
authors.forename: Edward G
authors.initials: EG
authors.lastname: Bartick
authors.forename: Mark L
authors.initials: ML
authors.lastname: Miller
authors.forename: Dennis C
authors.initials: DC
authors.lastname: Ward
authors.forename: Robert F
authors.initials: RF
authors.lastname: Mothershead