裂解气相色谱法分析蓝色中性笔字迹的书写墨水种类及墨迹随书写时间的变化规律

中性笔是当前比较流行的一种书写工具,其墨水多采用颜料作为色料成分,很难用水和有机溶剂进行提取,故无法利用分析圆珠笔油墨和水性笔墨水所采用的气相色谱或高效液相色谱等方法进行检验。目前在法庭科学领域内还没有一种有效的方法用于分析中性笔字迹的书写墨水。采用裂解气相色谱法分析了蓝色中性笔字迹的书写墨水,根据色谱峰的个数和保留时间将收集的65个样品分成3类,其中大部分样品属于具有铜酞菁颜料主要色谱峰的第二大类。色谱峰的保留时间和峰面积比值的分析结果表明所建立的分析方法重现性好且稳定。在此基础上,对蓝色中性笔墨迹随书写时间的变化规律进行了初步研究,得出了老化曲线。

Classification of Blue Gel Inks and Investigation of Change Rule of the Ink with Writing Age Using Pyrolysis Gas Chromatography

Gel ink pen (neutral pen) is a new popular pen. Its coloring matters are usually pigments which could not be extracted by water or organic solvents. Therefore, the methods of gas chromatography and high performance liquid chromatography for analyzing the inks of ball-point pen and water-based pen cannot be used here. There are no effective methods to identify gel inks in forensic science up to now. Pyrolysis gas chromatography (Py-GC) was used to analyze 65 different blue gel inks in this report. The pyrolysis was performed with a CZ-100 pyroprobe system using a coil filament with a quartz sample tube at 770 degrees C for 10 s. Agilent-6890N Gas Chromatograph was used with a nitrogen-phosphorus detector. A DM-5 Dikma Technology column (30 m x 0.32 mm x 0.25 microm) was used. Based upon the number and retention time of peaks in the pyrograms, the gel inks were separated into 3 classes. The most of the gel inks fell into the second group which have two characteristic peaks of copper phthalocyanine pigment. The results showed that the retention times and ratio of the peak areas were stable and reproducible. The writing age of blue gel ink was primarily investigated by the relative change rule of the main components in the ink, and the curves of writing age was obtained.