Ink dating, part I: Statistical distribution of selected ageing parameters in a ballpoint inks reference population

Abstract

The development of ink dating methods requires an important amount of work in order to be reliably applicable in practice. Major tasks include the definition of ageing parameters to monitor ink ageing. An adequate parameter should ideally fulfil the following criteria: it should evolve as a function of time in a monotonic way, be measurable in a majority of ink entries, be as accurate and reproducible as possible, and finally it should not be influenced too much by transfer and storage conditions. This work aimed at evaluating the potential of seven ageing parameters for ink dating purposes: the phenoxyethanol quantity, relative peak areas (RPA), three solvent loss ratios (R%, R%*, NR%) and two solvent loss parameters (R NR). These were calculated over approximately one year for 25 inks selected from a large database to represent different ageing behaviours. Ink entries were analysed using liquid extraction followed by GC/MS analysis. Results showed that natural ageing parameters (NR% and NR) were not suitable ageing parameters for ink entries older than a few weeks. RPA used other compounds present in ink formulations in combination to PE in order to normalise the results. However, it presented particular difficulties as they could not be defined for all inks and were thus applicable only for 64% of the studied inks. Finally, the PE quantity, R% and R allowed to follow the ageing of the selected inks over the whole time frame and were identified as the most promising. These were thus selected to test three different interpretation models in the second part of this article. The possibilities and limitations of ink dating methods will be discussed in a legal perspective.

Figures of Merit Evaluation of Gc/MS Method for Quantification of 2-Phenoxyethanol From Ballpoint Pen Ink Lines and Determination of the Influence of Support Paper on Solvent Extraction

“…Very recently, Koenig and Weyermann 18 continued this study and concluded testing seven ageing parameters for ink dating purposes: the phenoxyethanol quantity, relative peak area (RPA), three solvent loss ratios (R%, R%*, NR%) and two solvent loss parameters (R NORM, NR NORM ) -that natural ageing parameters (NR% and NR NORM ) were not suitable ageing parameters for ink entries older than a few weeks. The R% ratio consist of the area of the 2-PE peak, decreased from the area of the 2-PE peak extracted from the same sample which would have been artificially aged, divided by the area of 2-PE and multiplied by 100.…”

“…Although the ballpoint pen ink is a complex matrix, the electron impact source of the Mass Spectrometer is able to complete ionize the 2-PE molecule, and in the literature authors until now did not report ionization suppression in GC/MS analysis of 2-PE in pen ink matrix. 12,18,26,27 Because of this, it is reliable to use the curve after injection of standard solutions to determine 2-PE after extraction process.…”

“…In the same way, Koenig and Weyermann 18 very recently published a study evaluating the potential of seven ageing parameters for ink dating purposes: phenoxyethanol quantity, relative peak areas (RPA), three solvent loss ratios (R%, R%*, NR%) and two solvent loss parameters (R NORM, NR NORM ). These were calculated over approximately one year for 25 inks selected from a large database to represent different ageing behaviours.…”

Preliminary Studies on the Absorbance Ratio Method Used to Determining the Age of Stamp‐pad Ink Seal

“…For nearly a century, many studies had been executed by document examiners in all over the world. Some results used to determine the dating of a questioned document were proved to be favorable (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). Many pathways and methods can be selected for determining the dating of a questioned document.…”

“…Many methods play an important role in determining the change degree of the material, for example, gas chromatography, liquid chromatography, Raman spectroscopy, thermal analysis, and extraction rate method. The above methods can be employed to determine the age of ballpoint pen ink, iron-based ink, gel pen ink, and jet-printing ink (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11).…”