Ink Aging Method

In our society, Forensic examination often involves questioned documents and requires to determine the date of writing inks. Since 1950s, forensic scientists of all countries in the world have taken great efforts to study and established many analytical techniques used in law cases, some analytical ways are accepted by many justice branch. But until now, the examination of questioned documents and dating writing inks is one of difficult problems in forensic science due to the complexity and detection interference of inks. So determination of questioned documents and dating writing inks are very important .The paper is as five parts:Chapter one introduced the major components of inks, summarized the recent advance of aging of inks, including relative aging and accelerated aging.Chapter two systematically analyzed on the ball point writing inks with Gas Chromatography (GC), the content of the volatile components in ball point ink were determined by gas chromatography (GC). The absorbance of the dyes in the ballpoint ink were measured by ultraviolet visible spectrometry (UV-Vis). A writing age curve of the blue ball point ink had been established by the ratio of the content of the volatile components and the dye, based on the identification of 109 kinds of ball point inks which are from both domestic and international origins. The change of benzyl alcohol or phenoxyethanol was tested with the writing age. Ball point inks of different kinds were detected and the repeatability of the experiment was investigated. The results indicated that the method is reliable and systematic.Chapter three determined the aging sample of pen inks by UV-Vis, selected appropriate extraction solvent and complexant, Iron(Fe) in inks had been chosen as internal reference substance . We established the aging curve by the ratio of the absorbance of dye and iron . The method can be used to discriminate pen inks on documents of six or eight months.Chapter four studied the L-extraction , selected the wild solvent and strong solvent . Not only this ,we also identified the same sample of ballpoint inks by TLC , UV-Vis and Electrochemistry in this way .Results showed that this method had good repeatability.Chapter five studied the relative time of writing inks by the variety of the dyes component. A method for comparison of ink entries on papers in different conditions was presented, pure dye writings and ballpoint pen inks were exposed to strong light, infrared light, ultraviolet light...