ISSN: 0022-1198
CODEN: JFSCA
Published Online: 19 February 2004
Page Count: 7

Differentiation of Black Gel Inks Using Optical and Chemical Techniques
Cantu, AA
Forensic Services Division, DC

LaPorte, GM
Forensic Services Division, DC

Wilson, JD
Forensic Services Division, DC

(Received 10 August 2003; accepted 8 November 2003)

Abstract

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.

Keywords:
forensic science, questioned documents, document examination, non-ballpoint inks, inks, gel inks, gel pens, thin layer chromatography, GC/MS, TLC

Paper ID: JFS2003262
DOI: 10.1520/JFS2003262
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