Characterization of ballpoint pen inks by thermal desorption and gas chromatography-mass spectrometry

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Characterization of ballpoint pen inks by thermal desorption and gas chromatography-mass spectrometry Bügler JH, Buchner H, Dallmayer A
Download this paper for $25 PDF (176K) View License Agreement Source: JFS (July 2005)

Abstract
The characterization of ink on paper is of importance for dating and comparing questioned ink entries in forensic document examination. Inks are commonly characterized by their colorant profile that is identified by well-established analytical methods. Numerous ink formulations show identical colorant profiles, though. In order to differentiate inks that are not distinguishable by colorant analysis, a method for the characterization of colorless ink ingredients, namely binders, solvents and additives is necessary. In this paper, we propose a technique for the analysis of colorless compounds in ballpoint inks using direct thermal desorption of the ink on paper followed by chemical analysis of the desorbed volatile compounds by gas chromatography-mass spectrometry. As compared to liquid extraction and subsequent analysis of the extracts, the technique avoids possible contamination risks. Sensitivity is very high due to the enrichment of volatile components by thermal desorption. Even from old samples, the chromatograms obtained by the method enable the determination of binder polymers, solvents and additives. Pure binders as used by ink manufacturers were analyzed for unambiguous assignment of analytical results to specific polymers. To prove the practical applicability, we analyzed 121 ballpoint pens, not all having the same colorant profile, and grouped the pens into resin and solvent categories.

Keywords:
composition, document examination, forensic science, gas chromatography-mass spectrometry, ink, questioned document, questioned documents, resin, thermal desorption, volatiles
ISSN: 0022-1198
Paper ID: JFS2004486
DOI: 10.1520/JFS2004486

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Author Bügler JH, Buchner H, Dallmayer A Title Characterization of ballpoint pen inks by thermal desorption and gas chromatography-mass spectrometry Symposium , Committee on

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