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[Determination of the writing age of blue ballpoint ink by gas chromatography].

A method of identifying the writing age of blue ballpoint ink has been established for imperative demand of forensic laboratory. The content of the volatile component in blue ballpoint ink was determined by gas chromatography (GC). The absorbance of the dye in the blue ballpoint ink was measured by ultraviolet-visible spectrometry (UV-Vis). A writing age curve of the blue ballpoint ink has been established by the ratio of the content of the volatile components and the dye, based on the identification of 74 kinds of blue ballpoint inks, from both domestic and international origins. The change of benzyl alcohol or phenoxyethyl alcohol was tested with the writing age. Blue ballpoint inks of different kinds were detected and the repeatability of the experiment was investigated. The results indicated that the method is reliable and systematic, and especially suitable for practical cases.