The dating of ink in questioned documents remains a significant challenge in forensic investigations in Vietnam and other countries. Many forensic examination methods have been usually applied to ensure the highest accuracy of the assessment results while maintaining high environment awareness. In this study, paper characteristics were physically tested to confirm source similarity, and the relative ink dating was established by high-performance thin-layer chromatography (HPTLC). Absolute ink dating by solvent and dye identification was performed by Raman spectrometry—a green technique, using a time-dependent degradation model for crystal violet and the comparison between 2-phenoxyethanol peak intensities. We found that the relative dating of the questioned document was 14 ± 3 months lesser than that of the reference samples, i.e., the absolute age of the questioned samples was estimated to be 24 ± 3 months. The combination of the conventional HPTLC method with the dynamic crystal violet degradation Raman model provides promising results for relative and absolute ink dating of ballpoint pens, which can be applied for documents written 1–15 years prior to the time of examination. The combination of the abovementioned methods demonstrated an acceptable error margin, affording highly practical applications in modern forensic science.

中文翻译：

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绿色与传统方法相结合的相对和绝对墨水年龄估算：以越南的圆珠笔墨水约会为例

在越南和其他国家的法医调查中，质疑文档中的墨水日期仍然是一项重大挑战。通常使用许多法医检查方法来确保评估结果的最高准确性，同时保持高度的环境意识。在这项研究中，对纸张特性进行了物理测试以确认来源的相似性，并通过高性能薄层色谱法（HPTLC）确定了相对墨水年代。通过溶剂和染料鉴定的绝对墨水定年法是通过拉曼光谱法（一种绿色技术）进行的，使用了随时间变化的结晶紫降解模型和2-苯氧基乙醇峰强度之间的比较。我们发现，有问题的文档的相对日期比参考样本的相对日期短了14±3个月，即 所质疑样品的绝对年龄估计为24±3个月。常规HPTLC方法与动态结晶紫降解拉曼模型的结合为圆珠笔的相对和绝对墨水测年提供了可喜的结果，可将其应用于在检查之前1到15年书写的文档。上述方法的组合显示出可接受的误差容限，在现代法医学中提供了高度实际的应用。