Forensic and Psychological Sciences Laboratory Egas Moniz, Campus Universitário-Quinta da Granja, Monte da Caparica, 2829-511 Caparica, Portugal.
Molecular Pathology and Forensic Biochemistry Laboratory, Centro de Investigação Interdisciplinar Egas Moniz (CiiEM), Instituto Universitário Egas Moniz (IUEM), Campus Universitário-Quinta da Granja, Monte da Caparica, 2829-511 Caparica, Portugal.
Molecules. 2023 Jun 15;28(12):4781. doi: 10.3390/molecules28124781.
One of the major challenges in forensic document analysis is estimating the age of ink deposition on a manually written document. The present work aims to develop and optimise a methodology, based on the evaporation of 2-phenoxyethanol (PE) over time, that can contribute to ink age estimation. A black BIC Crystal Ballpoint Pen was purchased in a commercial area, and ink deposition began in September 2016 over 1095 days. For each ink sample, 20 microdiscs were subjected to n-hexane extraction in the presence of an internal standard (ethyl benzoate) followed by derivatisation with a silylation reagent. A gas chromatography-mass spectrometry (GC/MS) method was optimised for PE-trimethylsilyl (PE-TMS) to characterise the ageing curve. The developed method presented good linearity between 0.5 and 50.0 μg mL, as well as limits of detection and quantification of 0.026 and 0.104 μg mL, respectively. It was possible to characterise PE-TMS concentration over time, which reveals a two-phase decay behaviour. First, there was a substantial decline between the 1st and the 33rd day of deposition, followed a by a stabilisation of the signal, which allowed to detect the presence of PE-TMS up to 3 years. Two unknown compounds were also present and allowed to identify three dating time frames for the same ink stroke: (i) between time 0 and 33 days, (ii) between time 34 and 109 days, and (iii) more than 109 days. The developed methodology allowed to characterise the behaviour of PE over time and to establish a relative dating of three-time frames.
在法医文件分析中，一个主要的挑战是估计手动书写文件上墨迹的沉积年龄。本工作旨在开发和优化一种方法，该方法基于 2-苯氧基乙醇（PE）随时间蒸发，可有助于估计墨迹的年龄。在商业区购买了一支黑色 BIC Crystal 圆珠笔，从 2016 年 9 月开始在 1095 天内进行墨迹沉积。对于每个墨迹样本，将 20 个微圆盘用正己烷提取，同时加入内标（苯甲酸乙酯），然后用硅烷化试剂衍生化。优化了气相色谱-质谱（GC/MS）方法，以对 PE-三甲基硅烷（PE-TMS）进行特征化，以描绘老化曲线。所开发的方法在 0.5 至 50.0 μg mL 之间具有良好的线性关系，检测限和定量限分别为 0.026 和 0.104 μg mL。可以随时间描绘 PE-TMS 浓度，揭示出两相衰减行为。首先，在沉积的第 1 天至第 33 天之间有明显的下降，然后信号稳定下来，这使得可以检测到存在 PE-TMS 长达 3 年。还存在两种未知化合物，允许鉴定同一墨迹的三个日期范围：（i）0 到 33 天之间，（ii）34 到 109 天之间，以及（iii）超过 109 天。所开发的方法允许描述 PE 随时间的行为，并建立三个时间范围的相对日期。
