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Ink aging by dye ratio: case study

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Author Affiliations

  • 1Institute of Forensic Science, Istanbul University, Cerrahpasa Medicine Faculty Fatih Campus, Istanbul, Turkey
  • 2Cerrahpasa Medicine Faculty, Istanbul University, Cerrahpasa Medicine Faculty Fatih Campus, Istanbul, Turkey
  • 3Institute of Forensic Science, Istanbul University, Cerrahpasa Medicine Faculty Fatih Campus, Istanbul, Turkey

Res. J. Forensic Sci., Volume 6, Issue (5), Pages 1-4, June,29 (2018)

Abstract

Ink age determination; Changes in the structure of the ink (demethylation of the stain, evaporation of the solvents and polymerization of the resins) on the document are determined by chromatographic and spectroscopic methods. The dyes that are generally used are crystal violet, methyl violet and Victoria blue. Due to light exposure, in time crystal violet transforms in to methyl violet and methyl violet in to tetra methyl pararosaniline. Detection of this change can be easily determined by chromatographic methods. In this study, in order to determine whether the texts, signatures and figures on the same bond were written at the same time, the ink age of crystal violet, methyl violet and Victoria blue dyes were determined by using high pressure liquid chromatography and a dye ratio technique. The detection range of the method used is 0.02-0.6 ng. The statistical evaluation of these methods were examined performing intra day (n=6) and inter day calibration (n=6) which were found to be satisfactory, with highly accurate and precise results. This phenomenon came to us in 2015. The arrangement date written on the bond is 16/05/2007 and the date of payment is written as 14/06/2007. What was asked of us was to determine whether there is a date difference between the signature on the bond and the writing in the address section and also if the date has been edited to display an older date rather than a newer date. Therefore, the ink samples were taken from the writing on the bond and analyzed using high pressure liquid chromatography, dye ratios were compared and evaluated by age.

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