- 學位論文
電噴灑雷射脫附游離質譜技術於墨材鑑定方法之開發與應用
Development and application of electrospray laser desorption ionization mass spectrometry for ink identification
摘要
墨材分析是問題文書鑑定中最重要且難解的項目，這是因為墨材種類繁多，又是決定文件及鈔票有效性的關鍵。實務上常發生以不同筆墨（含可擦筆）修改原有內容或改變墨材製作順序來偽變造文件，但因現有筆墨成分配方相近，致鑑別難度增加；另因複製技術提升，使偽鈔品質更近似真鈔而不易辨識。面對上揭墨材問題，已難僅憑過去光學方法獲得解決，故本研究利用電噴灑雷射脫附游離質譜法（ELDI/MS）先建立檢驗各類筆墨及鈔票油墨之方法，並完成方法精密度評估；其次，運用ELDI/MS及實務上常用之紅外線冷光（IRL）、紅外線反射（IRR）等三種方法，對紙上172支黑色筆墨與43支藍色筆墨進行單法及結合多法之鑑別與比較，結果顯示ELDI/MS對黑、藍色筆墨之鑑別力均明顯優於IRL及IRR，即使結合上述三法之總體鑑別力也與ELDI/MS單法無明顯差異；此外，ELDI/MS能偵測到可擦筆經擦拭後殘留於紙面之微量筆墨，也可用來辨識文件上不同墨材之交疊順序；另ELDI/MS能區別千元新臺幣與百元美鈔兩者真、偽品（含不同部位）油墨質譜訊號之差異，進而可運用PCA軟體來進行大量鈔票檢品之分析。綜上可知，所建立的ELDI/MS不僅可直接檢出分析物成分，提供準確客觀結果，且僅對檢品表面造成不易察覺之外觀微破壞，非常符合鑑定實務需求，為一「簡單、快速、靈敏、準確」鑑定文件及鈔票偽變造之新式化學方法，可成功克服當前的鑑定瓶頸。
並列摘要
Ink analysis is the most important and difficult part of forensic examinations of questioned documents, because inks that have great variety can be used to determine the authenticity or validity of documents and banknotes. Documents are often falsified or altered using the different pens ( including erasable pens ) or changing the ink sequence. However, due to similar components of some inks that exist in the market, it is more difficult to differentiate them. In addition, modern copying techniques have also made harder to differentiate between high-quality fakes and authentic currencies. Because these ink problems of documents and banknotes are difficult for the spectroscopic imaging and microscopic examination to resolve, electrospray laser desorption ionization mass spectrometry (ELDI/MS) is used to establish a new method for examining the inks of the documents and banknotes. In this study, method effectiveness were firstly confirmed. Secondly, ELDI/MS, infrared luminescence (IRL) and infrared reflectance (IRR) were used to differentiate among 172 black inks and 43 blue inks on papers. It was found that the ability of discrimination among black or blue inks using ELDI/MS was significantly better than the one of IRL and IRR. Even an overall discriminating power of these three methods combined did not have much more improvement. Trace ink compounds remaining in visible and invisible erasable pen ink-lines were also successfully detected by ELDI/MS. Furthermore, the chemicals in different layer of inks on the documents were characterized by ELDI/MS. In addition, ELDI/MS was used to distinguish authentic banknotes from counterfeits of the NT$1000 and US$100 bills by detecting their surface chemical compositions at different ink regions. ELDI/MS also could distinguish large amount of banknotes analyzed by principle component analysis (PCA) using commercial software. From all experimental results, ELDI/MS made the examinations more precisely and objectively, and resulted in minimal damage to the documents and the banknotes. Thus, ELDI/MS is demonstrated to be used as a simple, rapid, sensitive and accurate tool to overcome the current ink problems of documents and banknotes in forensic science.