Bügler Jürgen H, Buchner Hans, Dallmayer Anton
Institute of Forensic Sciences, Bavarian State Bureau of Investigation, Munich, Germany.
J Forensic Sci. 2008 Jul;53(4):982-8. doi: 10.1111/j.1556-4029.2008.00745.x.
Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed.
间接测定法和直接测定法。间接测定法是基于对墨水进行化学分析，然后与参考样本集中已知的样本进行比较。该样本集应包含有关墨水的信息，包括市场推出日期。这种方法可能会检测到时代错误。第二种方法是基于测量随时间变化的墨水成分。分析圆珠笔墨水中的溶剂可能是确定纸张上墨水年代的一个有用参数。在之前的一项研究中，作者证明了直接从纸张上对墨水进行热脱附，然后使用气相色谱-质谱联用仪（GC-MS）进行化学分析这一方法，对于表征墨水粘结剂树脂和溶剂来说是一种很有前景的方法。初步测试表明，监测纸张上墨水溶剂的蒸发并不是一种适用于墨水年代测定的方法。对纸张上的墨水分两步进行热分析发现，新鲜墨水在一定低温下的规定时间段内会释放出相对量的溶剂，随着墨水老化，该相对量会减少。因此，在一定低温下释放的这种溶剂相对量及其随时间的减少量，可用于估计墨水的年代。在85种不同年代的墨水中研究了这个与年代相关的参数，这些墨水的年代跨度从1周到1.5年不等。研究发现，一些墨水在几个月的时间内，这个参数会显著下降，并且在这段时间内可以监测到老化过程。然而，对于其他墨水，与年代相关的参数下降相对较快，例如在几天内就降至一个恒定水平，这对于实际案件工作来说可能太快了。基于这些结果，开发了一种评估纸张上圆珠笔墨水年代的通用程序。
