Evaluation of the Photodegradation of Crystal Violet upon Light Exposure by Mass Spectrometric and Spectroscopic Methods

Détails

ID Serval
serval:BIB_C8BA371FE00C
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Evaluation of the Photodegradation of Crystal Violet upon Light Exposure by Mass Spectrometric and Spectroscopic Methods
Périodique
Journal of Forensic Sciences
Auteur(s)
Weyermann C., Kirsch D., Costa Vera C., Spengler B.
ISSN
0022-1198
Statut éditorial
Publié
Date de publication
03/2009
Peer-reviewed
Oui
Volume
54
Numéro
2
Pages
339-345
Langue
anglais
Résumé
Crystal violet is a very common dye in ballpoint ink. Recent research suggests that the degradation of triarylmethane dyes gives an indication of the age of a ballpoint pen entry on a document. The main problem for the quantitative evaluation of the degradation is that it is highly dependent on the exposure to light. Moreover additional factors, such as additives and substrate play an important role in this process. The aim of this work is to compare the degradation pathways of the pure dye in water and ethanol upon exposure to xenon light by UV/VIS spectrophotometry and laser desorption ionisation. Significant differences have been observed in the products and the kinetics of the degradation. N-demethylation, an expected decomposition process, was found to take place only in aqueous solution and kinetics calculations showed that the degradation occurred 2.5 times faster in ethanol compared to water. The degradation of crystal violet in inks from 4 ballpoint pens on paper was also studied for entries made over 2 to 3 years. It was observed that degradation reactions were quenched by the presence of another dye due to competitive absorption. It was also observed that the thickness of a stroke (concentration of ink) influenced the degradation process. In the absence of light only one ballpoint pen showed slight degradation. A better understanding of the influence of the paper, ink composition and storage conditions is necessary to interpret correctly the age of an ink based on the degradation of dyes.
Mots-clé
forensic, laser mass spectrometry, UV-VIS spectroscopy, MALDI-MS, cationic triarylmethane dyes, crystal violet, aging, ink
Création de la notice
19/11/2008 12:22
Dernière modification de la notice
03/03/2018 21:21
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