Examination of Firearms Review: 2007 to 2010 - Interpol

Zlotnick et al [108] suggests the use of Raman spectroscopy and micro Fourier
transform infrared (FT-IR) analysis among other more destructive analytical techniques
(LA ICP MS, PY-GC/MS and SEM), because of the inefficiency of the TLC technique.
His results underline that the document examiners must multiply analytical methods to
obtain a best discrimination of toners printings, when they compare toner based
documents between them.
Higashikawa et al [104] proposes a similar approach based on: SEM/EDX, PY/GC/MS,
FTIR and HPLC.
Besides, Zlotnick et al [108] and Higashikawa et al [104], uses the scanning electron
microscopy (SEM) to obtain information on morphological observations or elemental
analysis. More destructive methods can produce very discriminating complementary
information. This is demonstrated by Higashikawa et al [104] who analyse photocopied
characters by pyrolysis gas chromatrography coupled mass spectrometry (PY-GC/MS)
to study resins, and by high performance liquid chromatography (HPLC) to examine
organic additives. Szynkowska et al [105] use the inductively coupled plasma time-offlight
mass spectrometry with laser ablation (LA-ICP-TOF-MS).
In their work, document examiners must also answer the following question: Did the
suspected laser printer print the toner-based questioned documents? To help them,
Tanaka [111] suggests an approach based on the correlation of photoreceptor defects to
electrophotographic documents. Indeed, the location of such defective areas on the
photoreceptors are visualized by plotting the voltage data for the entire circumference
and length of the photoreceptor using automated equipment for testing the electrical
properties of photoreceptors in the electrophotographic industry. These defective areas
are then compared to individual defects on the printed pages to determine whether a
correlation between them is possible.
7. Inkjet
Szafarska et al [115] emphasise that chemical analysis of inkjet printer inks has become
increasingly important in forensic research due to the extensive use of inkjet technology
by counterfeiters. Therefore, the ability to differentiate between inkjet inks is of great
interest in document examination. He suggests using the capillary electrophoresis
technique, with simplified stages of extraction.
For similar reasons, Donnelly et al [116] analyses inkjet inks by LDMS to determine the
number of inks used by a printer and the chemical composition of the colorants.
For his part, LaPorte et al [118] tested an emergent methodology for the identification of
coloured inkjet inks: Direct Analysis in Real Time – Mass spectrometry (DART -MS).
This analytical technique, virtually non-destructive, involves very little sample
preparation and allows creation of a spectral searchable database.
Boileau et al [119] are interested in the analysis of black inkjet printed inks with thin layer
chromatography (TLC), high performance liquid chromatography (HPLC), pyrolysis gas
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