Ink dating using thermal desorption and gas chromatography/mass spectrometry: comparison of results obtained in two laboratories.
An ink dating method based on solvent analysis was recently developed using thermal desorption followed by gas chromatography/mass spectrometry (GC/MS) and is currently implemented in several forensic laboratories. The main aims of this work were to implement this method in a new laboratory to evaluate whether results were comparable at three levels: (i) validation criteria, (ii) aging curves, and (iii) results interpretation. While the results were indeed comparable in terms of validation, the method proved to be very sensitive to maintenances. Moreover, the aging curves were influenced by ink composition, as well as storage conditions (particularly when the samples were not stored in "normal" room conditions). Finally, as current interpretation models showed limitations, an alternative model based on slope calculation was proposed. However, in the future, a probabilistic approach may represent a better solution to deal with ink sample inhomogeneity.
Ecole des Sciences Criminelles, Institut de Police Scientifique, University of Lausanne, Bâtiment Batochime, 1015, Lausanne-Dorigny, Switzerland; Bundeskriminalamt, Forensic Science Institute, 651, Wiesbaden, Germany.
Agnès
A
Koenig
Jürgen
J
Bügler
Dieter
D
Kirsch
Fritz
F
Köhler
Céline
C
Weyermann
aging; forensic science; gas chromatography/mass spectrometry; ink dating; interpretation; questioned documents; solvent; thermal desorption