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

Abstract

Brazilian Forensic Scientists are frequently asked about ballpoint pen manuscripts chronology in documents suspected to be forged. In the recent years, many methods like quantification of 2-PE (2-phenoxyethanol) have been developed on this subject. The validation of these methods only recently has been a concern between scientific forensic community. Researchers studied the behavior of ink on ageing, but few of them concerned about the influence of the paper on the extraction of 2-PE. This study performed the figures of merit evaluation of the quantification of 2-PE using GC/MS, testing the main parameters involved in the reliability of the method (linearity, repeatability, limits of detection and quantification, accuracy and robustness). After, based on a full factorial design with four factors and two repetitions, the authors tested kind of paper, grammage of paper, ink color and three ink ages, to verify the paper influence on the quantity of 2-PE from ink, trough GC/MS analysis. The merit parameters evaluation showed that the method is linear, precise, accurate and robust. The results for the effect of paper showed main effects of the factors and the existence of interactions effects between the kind of paper and paper grammage, and between the kind of paper and other factors.

Interpol review of questioned documents 2016–2019

“…Five studies [ [67] , [68] , [69] , [70] , [71] ] focused on the analysis by GC/MS of phenoxyethanol (PE) of ballpoint inks and, its decrease over time.…”

“…De Carvalho C. and al [ 69 ] tested firstly the main parameters involved in the reliability of the method (linearity, repeatability, limits of detection and quantification, accuracy and robustness). In a second part, they tested the paper influence on the quantity of PE from ink.…”

Blue and Black Ballpoint Pen Inks: a Systematic Review for Ink Characterization and Dating Analysis

“…Despite the static dating method, which is related to ink characterization, there are two possibilities for ink dating, considering the inks' components transformations with time 3,4 For both relative and dynamic dating methods, it is necessary to have methods that are capable to detect the ink changes over time. Table 2 shows the most recent studies involving those methods [64][65][66][67][68][69][70][71][72][73][74][75][76][77][78] . The majority of the studies are based on the monitoring of solvents as they evaporate over time, but there are also studies based on the degradation of the dyes or resins.…”

“…Several studies have been using the 2-PE solvent quantification according to the inks' age, and gas chromatography coupled to mass spectrometry (GC-MS) or coupled with Flame Ionization Detection (GC-FID) is still the established method for the 2-PE quantification 64,65,67,[71][72][73]78 .…”

“…Carvalho et al, 2018 64 2-phenoxyethanol (solvent) -25 different inks chosen as representative of the different ageing behaviours Ink line cut from paper extracted with chloroform…”