ИСТИНА

Problem of documents examination exists thousands of years. This direction now includes both forensic examination and technology, history, art and other issues. Naturally, such an examination requires efforts of huge number experts, but the role of chemical analysis has always been paramount. The main feature of text documents chemical analysis is the need for sensitive methods due to the small amount of present substances, the need to obtain extensive information not only about the composition of the ink and the paper, but the interaction of these materials, aging. Nowadays there are large diversity types of paper and pen inks, due to this aspect the task of identification and determination the components becomes more complex and difficult using only a priori information. The aim of this work was to develop new LC-MS/MS procedure which allows accurate identification of dyes in ballpoint pen inks of the following firms: Beifa, Corvina, BIC, Pilot. A novel approach for the identification of dyes in the ballpoint pen inks by flow injection method with LC-MS/MS and UV-detection without using of standard dye samples has been established. Sample preparation procedure for extraction strokes of ballpoint pens in documents has been developed. Characteristic group of ions for each sample of ballpoint pen ink corresponding present dyes has been determined. Chromatographic separation conditions for identified dyes has been optimized on reversed-phase sorbent based on silica gel. The best composition of the mobile phase for the dyes mixture chromatographic separation was 0.1% aqueous formic acid and acetonitrile. Dyes detection was carried out using tandem mass spectrometry with electrospray ionization in positive and negative modes after reversed phase liquid chromatography separation. Dye composition of ink was additionally confirmed comparing the data obtained from literature.