Problems of Forensic Sciences 2010 Vol. 83 (LXXXIII) 233-242
INVESTIGATION INTO THE POSSIBILITY OF IDENTIFYING DYES IN THE PARAROSANILINE DERIVATIVES GROUP IN VIOLETBLUE BALLPOINT PEN INKS BY MICROSPECTROPHOTOMETRY IN THE VISIBLE RANGE (MSP-VIS)
Beata M. TRZCIŃSKA
Department of Criminalistics, Institute of Forensic Research, Kraków, Poland
Streszczenie
Spectrometry in the visible range could be a useful technique in forensic examination of documents, e.g. it could enable creation of a numerical description of the colour of writing materials used in the writing process, or it could be used for determination of the kind of dye present in writing materials, or in comparative studies. The main components of ballpoint pen inks are dye(s) and carriers. The aim of the research was to establish whether identification of the main component is possible on the basis of Vis spectra of violet-blue ballpoint pen inks. Analyses were carried out for dyes named methyl violet and crystal violet manufactured by various producers or two-component specimens prepared for research purposes. One of the components was methyl violet or crystal violet, and the second one was the carrier – olein or ethylene glycol. These specimens were deposited on paper in the form of thin lines (imitation of hand writing executed by a thin ball point pen). Specimens were analysed in reflection mode, dyes by both reflection and transmission techniques. The spectra of a particular dye obtained by the two techniques differed from each
other. The spectra of (different) dyes, both reflection and transmission ones, (also) differed from each other. At the same time, spectra of specimens were similar, which suggests that the kind of carrier and dye did not have an influence on the result. Therefore, the MSP-Vis method can only be used as a screening method for group identification of the main dye present in ball point pen inks. The identification process could be supported by an appropriate data base of Vis spectra.
Słowa kluczowe
Crystal violet; Gentian violet; Methyl violet; Writing materials; Methyl derivatives of pararosaniline; MSP-Vis; Ball point pen inks.