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MASS SPECTROMETRY

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  p540-541

2026-08-26

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MASS SPECTROMETRY

Mass spectrometry, with and without gas chromatography, has been used for the analysis of inks. Laser desorption mass spectrometry has been especially effective because the ink does not have to be removed from the paper first. A piece of paper with ink writing on it can be directly introduced into the instrument. It is also essentially nondestructive. Laser desorption can be used to track an ink dye as it ages. When dyes age, they undergo chemical degradation. One popular ballpoint pen ink dye, methyl violet, degrades by losing CH₃ groups, replacing them with hydrogen atoms. This results in the loss of 14 mass units from the molecule. Figures 1(a) and (b) show how methyl violet degrades and an aging study on a typical ballpoint pen.

FIGURE 1 (a) The degradation of methyl violet. Each degradation causes the replacement of a methyl group with a hydrogen atom, resulting in the loss of 14 mass units. (b) An artificial aging study of methyl violet dye in a blue, ballpoint pen, by tracking with laser desorption mass spectrometry.