DOCUMENT ANALYSIS | Ink Analysis

Analysis of the Aging Processes of Writing Ink: Raman Spectroscopy versus Gas Chromatography Aspects

“…Electronic absorption spectra of writing inks of the A-, B-and C-types. The comparison of Raman peaks of dyes as well as data on the thermal degradation of volatile components and dyes [16] show that the field of application of Raman spectroscopy can be expanded and that this technique can be used not only for analysis in forensic science (the identification of writing ink dyes and the determination of the sequence of the placing of inscriptions, drawings, and stamps on paper [1,2,13,17,18]), but also for the estimation of age of the material placed on the paper beyond the period of chromatography capabilities.…”

“…In turn, for convenience and better understanding, in the proposed methodology, we have to appeal to some previously reported results [16]. The methodological distinction of this from similar studies [1,2,13,17,18] was in considering the fact that the peak intensity in Raman spectrum also depends on the concentration of the studied compound within the focal spot of the laser beam, which was impossible to control in our case. Thus, in order to eliminate the influence of the concentration factor, we used the ratio of intensities instead of absolute intensity values.…”

“…In a variety of cases, in order to hide the fact of falsification, documents are heated or exposed to artificial or natural light sources. Thus, the disclosure of such falsification is an important legal and social task [1,2].…”

“…All writing inks consist of a dye component or a mixture of dyes, as well as a binding substance known as a vehicle composed of several solvents and additives responsible for the physicochemical properties of inks (including lubricants, corrosion inhibitors, emulsifying agents, buffers, surfactants, and various other components) [2][3][4]. All ingredients in the ink mixture can yield important analytical information to the forensic document examiner.…”

“…Glycols have been predominantly used as solvents since 1950. In turn, the most widespread solvents currently used are glycerol, tri-, tetra-, pentaethylene glycols, fenoxyetanol, phenoxyetoxy ethanol, benzyl alcohol, 2-pyrrolidone and butylene glycol [2,6].…”