Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor's Name

José R. Almirall

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Piero R. Gardinali

Second Advisor's Committee Title

Committee Member

Third Advisor's Name

James M. Quirke

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Sneh Gulati

Fourth Advisor's Committee Title

Committee Member

Fifth Advisor's Name

Antonio A. Cantú

Fifth Advisor's Committee Title

Committee Member

Keywords

Analytical Chemistry, Forensic Science, Questioned Document Examination, Ink analysis, Qualitative Analysis, Organic Chemical Characterization

Date of Defense

10-27-2016

Abstract

Improvements in printing technology and the wide accessibility of advanced printers has resulted in an increase in counterfeiting. Of particular interest to forensic document examiners, ink analysis of security documents has emerged as an important tool for the analysis, comparison, and association of inks to a potential production source. In this study, methods were developed for Py-GC/MS, ATR-FTIR, DART-MS, and MALDI-MS analyses of printing inks of four classes: 78 inkjet inks, 76 toners, 79 offset inks, and 86 intaglio inks in order to generate information on the organic chemical characterization of the inks to determine the ability to associate and discriminate the inks for uses in security document examinations. The suite of analytical techniques evaluated in the study focused on having the following analytical characteristics: 1) rapid analysis time, 2) little-to-no sample preparation, 3) minimal destructiveness to the sample, 4) allow for association of inks with the same source of origin as well as discrimination of inks originating from different sources. As a result of this study, a novel searchable library database of inks was developed for use with each analytical chemical method that allows for data fusion.

Py-GC/MS analysis was used to achieve >63% discrimination of toner inks on the basis of the characterization of polymer degradation products. The combination of a protocol implementing first ATR-FTIR and subsequently DART-MS analysis resulted in >96% discrimination for toners, 95% for inkjet, >92% for offset, and >54% for intaglio. In addition, a case study was performed using DART-MS to illustrate its utility as a tool for ink analysis in document examination. The results of MALDI-MS analyses from two different instruments resulted in >90% discrimination of a subset of all inks by characterizing the colorant molecules present in ink formulations. A study characterizing luminescent compounds present in the formulation of inks in crossed-line intersections was performed using a combination of MALDI-MS, LC-MS, and TLC. Overall, it was shown that the combination of analytical techniques included within this dissertation can provide information on the organic chemical composition of four classes of printing inks, which is useful for the future of document examination.

Identifier

FIDC001179

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