(Received 8 July 2002; accepted 31 May 2002)
Published Online: November
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In questioned document examination and ink dating, it has been assumed that the ink inside of a pen cartridge does not begin aging until the ink is dispensed onto paper. Positive ion laser desorption (LD) mass spectra were obtained of ink-on-paper samples containing methyl violet, from new and old pens. Mass spectral studies with methyl violet have established the mechanism for how the dye degrades over time, and have provided structural information concerning the dye's degradation products. This information was used as an indication of the relative age of ink on paper. The LD mass spectrum of the ink from a new pen was indicative of “new” ink, whereas the spectra of the ink found in some older pens may appear to be either new or old. The ink from most of the old pens studied appears not to have aged, supporting the common assumption, whereas other ink samples produced “aged” ink spectra, suggesting otherwise.
Michigan State University, East Lansing, MI
School of Criminal Justice, Michigan State University, East Lansing, MI
Stock #: JFS15563J