Kao Yi-Ying, Cheng Sy-Chyi, Cheng Chu-Nian, Shiea Jentaie, Ho Hsiu-O
College of Pharmacy, Taipei Medical University, Taipei, Taiwan; Investigation Bureau, Ministry of Justice, New Taipei City, Taiwan.
J Mass Spectrom. 2014 Jun;49(6):445-51. doi: 10.1002/jms.3356.
Writings made with erasable pens on paper surfaces can either be rubbed off with an eraser or rendered invisible by changing the temperature of the ink. However, trace ink compounds still remain in the paper fibers even after rubbing or rendering. The detection of these ink compounds from erased handwritings will be helpful in knowing the written history of the paper. In this study, electrospray-assisted laser desorption ionization/mass spectrometry was used to characterize trace ink compounds remaining in visible and invisible ink lines. The ink compounds were desorbed from the paper surface by irradiating the handwritings with a pulsed laser beam; the desorbed analytes were subsequently ionized in an electrospray plume and detected by a quadrupole time-of-flight mass spectrometry mass analyzer. Because of the high spatial resolution of the laser beam, electrospray-assisted laser desorption ionization/mass spectrometry analysis resulted in minimal damage to the sample documents.
用可擦除笔在纸张表面书写的字迹，既可以用橡皮擦除，也可以通过改变墨水温度使其不可见。然而，即使经过擦拭或使其不可见处理后，微量墨水成分仍会残留在纸张纤维中。从擦除字迹中检测这些墨水成分，将有助于了解纸张的书写历史。在本研究中，采用电喷雾辅助激光解吸电离/质谱法对可见和不可见墨线中残留的微量墨水成分进行表征。通过用脉冲激光束照射字迹，使墨水成分从纸张表面解吸；随后，解吸的分析物在电喷雾羽流中离子化，并由四极杆飞行时间质谱仪进行检测。由于激光束具有高空间分辨率，电喷雾辅助激光解吸电离/质谱分析对样本文件造成的损伤极小。
