NCJ Number
145755
Journal
Journal of Forensic Sciences Volume: 38 Issue: 4 Dated: (July 1993) Pages: 843-863
Date Published
1993
Length
21 pages
Annotation
During the past two decades, the increase in the use of photocopying machines has caused forensic scientists practical difficulties in identifying the origin of copied documents.
Abstract
The analysis of chemical properties of toners can facilitate photocopier discrimination. Several techniques have been used to differentiate photocopy toners, including infrared spectrosopy, pyrolysis gas chromatography (PY- GC)/mass spectrometry, and scanning electron microscope- energy dispersive x-ray analysis. In the current study, a Curie-point pyrolyzer, a dual wide-bore capillary column GC equipped with dual flame ionization detectors, and a personal computer were connected online. The differentiation of photocopier toners was based on comparing retention indexes and conventional pattern recognition. Results showed that a modified PY-GC technique is useful in the differentiation of photocopier toners and that the computer- assisted library search based on retention index comparison is a powerful approach to locating suspect photocopying machines. 22 references, 4 tables, and 7 figures