Evaluation of the Photodegradation of Crystal Violet upon Light Exposure by Mass Spectrometric and Spectroscopic Methods
- 24 February 2009
- journal article
- research article
- Published by Wiley in Journal of Forensic Sciences
- Vol. 54 (2), 339-345
- https://doi.org/10.1111/j.1556-4029.2008.00975.x
Abstract
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 ionization. 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 four ballpoint pens on paper was also studied for entries made over 2-3 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.Keywords
This publication has 16 references indexed in Scilit:
- The potential of artificial aging for modelling of natural aging processes of ballpoint inkForensic Science International, 2008
- Photofading of ballpoint dyes studied on paper by LDI and MALDI MSJournal of the American Society for Mass Spectrometry, 2006
- Ballpoint Pen Inks: Characterization by Positive and Negative Ion-Electrospray Ionization Mass Spectrometry for the Forensic Examination of Writing InksJournal of Forensic Sciences, 2002
- Changes in Composition of Ballpoint Pen Inks on Aging in DarknessJournal of Forensic Sciences, 2002
- The inhibition of triphenylmethane primary dye fading in carbonless copying paper systems by singlet oxygen quenching bis(dithiocarbamato)nickel(II) complexesDyes and Pigments, 2002
- HPLC Analysis of Ballpoint Pen Inks Stored at Different Light ConditionsJournal of Forensic Sciences, 2001
- Biodegradation of methyl violet by Pseudomonas mendocina MCM B-402Applied Microbiology and Biotechnology, 1999
- Two competitive primary processes in the photodegradation of cationic triarylmethane dyes under visible irradiation in TiO2 dispersionsNew Journal of Chemistry, 1999
- A Microspectrophotometric Method for Dating Ballpoint Inks—A Feasibility StudyJournal of Forensic Sciences, 1995
- Lightfastness and spectroscopic properties of basic triphenylmethane dyes: Effect of the substrateDyes and Pigments, 1980