Laboratory for Forensic Chemistry, Faculty of Chemistry, Jagiellonian University, 3 Ingardena St., 30-060 Krakow, Poland.
Forensic Sci Int. 2013 Dec 10;233(1-3):140-8. doi: 10.1016/j.forsciint.2013.09.006. Epub 2013 Sep 12.
Questioned document examination in a wide variety of criminal and civil cases often focuses on the identification and comparison of stamp inks. Increasingly frequent counterfeiting of documents, especially those that have been stamped, has led to a growing need for instrumental methods that will allow an in-depth examination of stamp inks on a document. Therefore, the usefulness of two capillary electrophoresis techniques: micellar electrophoretic capillary chromatography with UV/Vis diode array detection (MECC-DAD) and capillary zone electrophoresis with electrospray mass spectrometric detection (CZE-ESI/MS) was verified for this purpose. Violet, red, blue and green stamp inks on paper surfaces were investigated. Electropherograms and mass spectra of inks purchased from 10 different producers were obtained in accordance with optimized and validated analytical procedures. It was shown that effective differentiation of individual inks was possible in terms of migration time and UV/Vis spectra provided that there was more than one characteristic peak. However, the most problematic inks with only one very similar (or identical) dye component - violet and blue ones - were additionally differentiated by CZE-MS. The obtained results showed that the proposed procedures can be useful for the objective analysis of questioned documents involving stamp inks. Consequently, the developed methods can be applied in the forensic field, including in the investigation of the authenticity of documents.
在各种刑事和民事案件中， questioned document examination（ questioned document 鉴定）通常侧重于印章油墨的鉴定和比较。越来越频繁的文件伪造，尤其是那些已经盖章的文件伪造，导致对文件上的印章油墨进行深入检查的仪器方法的需求日益增长。因此，为了达到这个目的，验证了两种毛细管电泳技术的有用性：胶束电动毛细管色谱与紫外/可见二极管阵列检测（MECC-DAD）和带有电喷雾质谱检测的毛细管区带电泳（CZE-ESI/MS）。研究了纸张表面上的紫色、红色、蓝色和绿色印章油墨。根据优化和验证的分析程序，获得了从 10 个不同生产商购买的油墨的电泳图谱和质谱。结果表明，只要有多个特征峰，就可以根据迁移时间和紫外/可见光谱有效地对各个油墨进行区分。然而，对于只有一个非常相似（或相同）染料成分的最具问题性的油墨 - 紫色和蓝色油墨 - 还可以通过 CZE-MS 进行额外区分。获得的结果表明，所提出的程序可用于涉及印章油墨的 questioned document 的客观分析。因此，所开发的方法可应用于法医领域，包括文件真实性的调查。
