ISSN: 0022-1198
CODEN: JFSCA
Published Online: 1 May 2003
Page Count: 6

Photodegradation and Laser Desorption Mass Spectrometry for the Characterization of Dyes Used in Red Pen Inks
(Received 30 December 2002; accepted 20 December 2002)

Abstract

Photodegradation and laser desorption mass spectrometry (LDMS) is a powerful combination of methods capable of characterizing dyes found in pen inks. Rhodamine dyes in pens that contain red ink were analyzed directly from paper (no extraction step is necessary). Inks exposed to incandescent light form photodegradation products (compounds with lower molecular weights than that of the intact dye) and in some instances, photoproducts (compounds with higher molecular weights than that of the intact dye). The degradation products and photoproducts can be detected with LDMS, and the results can be used for dye identification. Advantages include: (1) the instrumental analysis takes less than a minute; (2) sample preparation is minimal; (3) LDMS is a minimally destructive technique; (4) incandescent light sources are inexpensive, safe to use, and readily available; and (5) isomeric dyes can be distinguished.

Keywords:
forensic science, questioned documents, laser desorption mass spectrometry, photodegradation, incandescent light, ink, dyes, rhodamine

Paper ID: JFS2002359
DOI: 10.1520/JFS2002359
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