Senior Samir, Hamed Ezzat, Masoud Mamdouh, Shehata Eman
Department of Chemistry, Faculty of Science, Alexandria University, Alexandria, Egypt.
J Forensic Sci. 2012 Jul;57(4):1087-93. doi: 10.1111/j.1556-4029.2012.02091.x. Epub 2012 Mar 5.
The ink of pens and ink extracted from lines on white photocopier paper of 10 blue ballpoint pens were subjected to ultraviolet-visible (UV-Vis) spectroscopy, infrared (IR), and high-performance thin-layer liquid chromatography (HPTLC). The R(f) values and color tones of the bands separated by thin-layer chromatography (TLC) analysis used to classify the writing inks into three groups. The principal component analysis (PCA) investigates the pen responsible for a piece of writing, and how time affects spectroscopy of written ink. PCA can differentiate between pen ink and ink line indicates the influence of solvent extraction process on the results. The PCA loadings are useful in individualization of a questioned ink from a database. The PCA of ink lines extracted at different times can be used to estimate the time at which a questioned document was written. The results proved that the UV-Vis spectra are effective tool to separate blue ballpoint pen ink in most cases rather than IR and HPTLC.
对10支蓝色圆珠笔在白色复印纸上书写的笔迹所提取的墨水进行了紫外可见（UV-Vis）光谱、红外（IR）光谱以及高效薄层液相色谱（HPTLC）分析。通过薄层色谱（TLC）分析得到的R(f)值和色带色调，可将书写墨水分为三组。主成分分析（PCA）用于调查书写所用的笔以及时间对书写墨水光谱的影响。PCA能够区分笔墨水和墨线，表明溶剂萃取过程对结果的影响。PCA载荷有助于从数据库中对可疑墨水进行个体化识别。对不同时间提取的墨线进行PCA可用于估计可疑文件的书写时间。结果证明，在大多数情况下，UV-Vis光谱是分离蓝色圆珠笔墨水的有效工具，而非IR和HPTLC。
