Differentiation of Black Gel Inks Using Optical and Chemical Techniques

Gel ink pens have become a common writing instrument in the United States. Questioned document examiners often attempt to optically differentiate gel inks from each other and from other non-ballpoint ink writings (e.g., those from roller-ball pens). Since early formulations were primarily pigment-ba...

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Bibliographic Details
Published in:Journal of forensic sciences 2004-03, Vol.49 (2), p.1-7
Main Authors: Wilson, JD, LaPorte, GM, Cantu, AA
Format: Article
Language:English
Subjects:
Chromatography
Forensic sciences
Ink & ink industry
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Summary:Gel ink pens have become a common writing instrument in the United States. Questioned document examiners often attempt to optically differentiate gel inks from each other and from other non-ballpoint ink writings (e.g., those from roller-ball pens). Since early formulations were primarily pigment-based, they do not elute when analyzed by thin-layer chromatography. However, recent gel ink formulations (i.e., within the past five years) include dye-based inks that can be easily separated. This study differentiates black gel inks using optical and chemical techniques. The techniques include: microscopy, visible and near infrared reflectance, near infrared luminescence, thin-layer chromatography (TLC), spot tests, and gas chromatography/mass spectrometry (GC/MS). As a result of this study a flow chart has been developed allowing for a systematic determination of a questioned ink. In addition, an analysis of volatile compounds found in gel inks revealed that there are some unique ingredients that may be found in gel inks that are not typically found in other non-ballpoint inks.
ISSN:0022-1198
1556-4029
DOI:10.1520/JFS2003262