NCJ Number
226554
Journal
Journal of Forensic Sciences Volume: 5 Issue: 2 Dated: March 2009 Pages: 339-345
Date Published
March 2009
Length
7 pages
Annotation
This study compared the degradation pathways of the pure dye crystal violet (a common dye in ballpoint ink) in water and ethanol upon exposure to xenon light by UV/VIS spectrophotometry and laser desorption ionization.
Abstract
The study demonstrated that the degradation pathways of the dye under exposure to xenon light were significantly different in water and ethanol. The proposed N-demethylation mechanism happened only in aqueous solution. 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. Degradation reactions were quenched by the presence of another dye due to competitive absorption. Two of the ballpoint pens contained additional dyes, whose spectral absorption competed with that of crystal violet, thus quenching the degradation. An effect of the total local concentration of the ink on an entry was also observed. All pens showed a high stability in the absence of light. The thickness of a stroke (concentration of ink) influenced the degradation process. Future research should provide a better understanding of the influence of the paper, ink composition, and storage conditions on degradation of ink dyes and consequently interpretations of the ink’s age. Descriptions of experimental procedures address the materials, instrumentation, UV/VIS spectrophotometry, dye degradation by exposure to light, procedures and treatments, and ballpoint pen entries. 9 figures and 22 references