An Improvement on Pyrolysis Gas Chromatography for the Differentiation of Photocopy Toners

Abstract

During the past two decades, the great increase of the use of photocopying machines has given the forensic scientists many practical difficulties in identifying the origins of copied documents. Analysis of chemical properties of toners can be helpful for photocopier discrimination. Several techniques including infrared spectroscopy (IR) pyrolysis gas chromatography/mass spectrometry (Py-GC-MS) and scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX) have been extensively used. In this study, a Curie-point pyrolyser, a dual wide-bore capillary column GC equipped with dual flame ionization detectors (FIDs) and a personal computer were connected online. The differentiation of photocopier toners, however, was based both on the comparison of retention indices and on conventional pattern recognition. The proposed method including the library search is quite simple, reliable and low-cost.

Toner Particles as Forensic Evidence: Microanalytical Characterization of Known Toner and Recognition of Toner in Environmental Samples*†‡

“…Over the past 30 years, there have been many studies on the analysis of toner, including an in‐depth three‐part series examining the forensic discrimination of different toner samples (6–8). Researchers have focused on the use of scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM‐EDS) (8–10); pyrolysis gas chromatography (py‐GC) (8,11–15); infrared spectroscopy, both diffuse reflectance and infrared‐reflection absorption (6,7,13–22); and thin layer chromatography (TLC) (19,23,24) for the analysis and comparison of toners, among others (9,15,25–27). In more recent years, Raman has additionally been suggested as a technique for the analysis of toner (27–30).…”

“…Researchers have focused on the use of scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) (8-10); pyrolysis gas chromatography (py-GC) (8,(11)(12)(13)(14)(15); infrared spectroscopy, both diffuse reflectance and infrared-reflection absorption (6,7,(13)(14)(15)(16)(17)(18)(19)(20)(21)(22); and thin layer chromatography (TLC) (19,23,24) for the analysis and comparison of toners, among others (9,15,(25)(26)(27). In more recent years, Raman has additionally been suggested as a technique for the analysis of toner (27)(28)(29)(30).…”

The assessment of the impact of induction spatial effects on magnetic flux measurements of toner‐printed documents to the detection of forged or altered documents

“…These authors also noted that the acquisition of spectra was not affected by the paper substrate [17]. The use of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) has also been investigated to improve the detection and differentiation of toners based primarily on the resin [18,19,20,21]. Elemental analysis methods have also been applied to characterize printing and photocopy toners: These methods included laser-induced breakdown spectroscopy (LIBS) [22,23], X-ray fluorescence (XRF) spectroscopy [24], laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) compared to scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) [25,26], and LA-ICP-MS compared to LIBS [27].…”

Forensic discrimination of photocopy and printer toners. III. Multivariate statistics applied to scanning electron microscopy and pyrolysis gas chromatography/mass spectrometry

“…Compounds used to classify toners in the first group included styrene, butyl methacrylate, methylheptyl acrylate, decyl methacrylate, styrene trimer, methyl methacrylate, and a peak of unknown composition. Chang et al [30] used a library search of Py-GC retention indices to differentiate 14 toner samples by their pyrolysis products. Brandi et al [10] found Py-GC to not provide any greater discriminating power than IR for copy toners.…”