Maind S D, Kumar S A, Chattopadhyay N, Gandhi Ch, Sudersanan M
Neutron Activation Analysis Unit of Central Forensic Science Laboratory, Hyderabad, Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
Forensic Sci Int. 2006 May 25;159(1):32-42. doi: 10.1016/j.forsciint.2005.05.037. Epub 2005 Aug 9.
Characterization and assessment of inks on sensitive documents for absolute/relative age determination is the challenging forensic problem in spite of practical difficulties. Tagging of ballpoint pen ink with suitable taggant(s) is a unique method to come out with definitive inferences on the detection of forgery in documents written with ballpoint pens. Selection of a proper taggant primarily depends on sensitivity of analytical determination and their absence in normal varieties of ink used for document writing. Rare-earth elements, from all technical considerations can be potential taggant(s) for inks. To ensure more compatibility with ink, 13 rare-earth thenoyltrifluoroacetonate chelates were prepared and characterized. The ballpoint pen inks were tagged with rare-earth thenoyltrifluoroacetonate chelates individually at about 1-100 ppm level depending on sensitivity of element under suitable optimized experimental conditions and instrumental sensitivity. Aliquots of such tagged ink having varying amounts of taggants were analyzed by ICP-MS and INAA. Satisfactory recoveries and a good linear relationship of intensity (signal) against concentrations/amounts were observed. Under the optimized experimental conditions, the detection limits were worked out. This study of tagging metal ions in combination with ICP-MS and NAA as an analytical tool can allow to draw various combination options based on different rare-earth chelates as suitable materials for tagging of ballpoint pen inks for absolute/relative age determination to aid in document related crime examination. The advantages and limitations of proposed analytical techniques are discussed.
尽管存在实际困难，但对敏感文件上的墨水进行表征和评估以确定绝对/相对年代仍然是一个具有挑战性的法医问题。用合适的标记剂标记圆珠笔墨水是一种独特的方法，可对用圆珠笔书写的文件中的伪造检测得出明确的推断。选择合适的标记剂主要取决于分析测定的灵敏度以及它们在用于文件书写的普通墨水中的不存在情况。从所有技术考虑来看，稀土元素可能是墨水的潜在标记剂。为确保与墨水有更好的兼容性，制备并表征了13种稀土噻吩甲酰三氟丙酮螯合物。在合适的优化实验条件和仪器灵敏度下，根据元素的灵敏度，将稀土噻吩甲酰三氟丙酮螯合物分别以约1-100 ppm的水平标记圆珠笔墨水。用ICP-MS和INAA分析了含有不同量标记剂的这种标记墨水的等分试样。观察到回收率令人满意，强度（信号）与浓度/量之间具有良好的线性关系。在优化的实验条件下，确定了检测限。这项将金属离子标记与ICP-MS和NAA作为分析工具相结合的研究，可以基于不同的稀土螯合物得出各种组合选项，作为标记圆珠笔墨水以确定绝对/相对年代的合适材料，以协助进行与文件相关的犯罪调查。讨论了所提出的分析技术的优点和局限性。
