Djozan Djavanshir, Baheri Tahmineh, Karimian Ghader, Shahidi Masomeh
Faculty of Chemistry, University of Tabriz, Tabriz, Iran.
Forensic Sci Int. 2008 Aug 6;179(2-3):199-205. doi: 10.1016/j.forsciint.2008.05.013. Epub 2008 Jul 17.
This article aims to provide a new and fast method for differentiation of inks on a questioned document. The data acquisition was carried out by designing specific image analysis software for evaluating thin layer chromatograms (TLC-IA). The ink spot was extracted from the document using methanol and separated by TLC using plastic sheet silica gel 60 without fluorescent indicator, and a mixture of ethyl acetate, ethanol, and water (70:35:30, v/v/v) as mobile phase. To discriminate between different pen inks, new software was designed on the basis of intensity profile of red, green, and blue (RGB) characteristic. In practice, after development of chromatogram, the chromatograms were scanned by ordinary office scanner, intensity profiles of RGB characteristics on the development straight of each sample were produced and compared with the mentioned software. RGB profiles of ballpoint inks from various manufacturers showed that the patterns in most cases were distinctly different from each other. This new method allowed discriminating among different pen inks with a high reliability and the discriminating power of 92.8%. Blue ballpoint pen inks of 41 different samples available on the local market were successfully analyzed and discriminated.
本文旨在提供一种用于鉴别可疑文件上墨水的全新快速方法。数据采集通过设计用于评估薄层色谱图（TLC - IA）的特定图像分析软件来进行。使用甲醇从文件中提取墨点，并使用不含荧光指示剂的塑料片硅胶60通过薄层色谱法进行分离，以乙酸乙酯、乙醇和水的混合物（70:35:30，v/v/v）作为流动相。为了区分不同的钢笔墨水，基于红、绿、蓝（RGB）特征的强度分布设计了新软件。实际上，在色谱图展开后，用普通办公扫描仪对色谱图进行扫描，生成每个样品展开条带上RGB特征的强度分布，并与上述软件进行比较。来自不同制造商的圆珠笔墨水的RGB分布表明，在大多数情况下，这些模式彼此明显不同。这种新方法能够以高可靠性区分不同的钢笔墨水，鉴别能力达92.8%。成功分析并鉴别了当地市场上可得的41个不同样品的蓝色圆珠笔墨水。
