LC-MS/MS法检测圆珠笔墨迹中碱性蓝7及其去乙基产物的降解变化

The aging behavior of Basic Blue 7 and its de-ethyl productsin ballpoint pen ink entries by LC-MS/MS

目的考察圆珠笔墨迹中碱性蓝7及其去乙基产物的降解变化,为圆珠笔墨迹书写时间的研究提供基础数据。方法用氙灯老化碱性蓝7以生成其5个去乙基产物。建立LC-MS/MS检测碱性蓝7及其去乙基产物的方法。制作圆珠笔墨迹样本,在室内自然光照条件下老化3个月,同时进行控制实验条件的氙灯老化和高温老化实验。结果碱性蓝7的相对含量持续下降,其第一、第二级去乙基产物E4、E3的相对含量相继达到最大值,剩余三个去乙基产物E2、E1和E0的相对含量在三个月内持续增加。结论碱性蓝7的相对含量与光的辐照能量呈指数函数关系,其去乙基产物E4、E3的相对含量与光的辐照能量呈二次函数关系。不同油墨中碱性蓝7的老化曲线不同。温度对碱性蓝7的降解基本没有影响。

Objective To study the aging behavior of Basic Blue 7 （BB7） and its five de-ethyl products in ink entries and inthis way provide some basic data for the forensic study to date blue ballpoint pen ink entries. Method BB7 was artificially agedby xenon light, resulting in the production of five de-ethyl products. A high performance liquid chromatography tandem massspectrometry （LC-MS/MS） method was developed for the analysis of these analytes. Afterwards, ink entries of nine ballpointpens were aged by daylight for three months. Furthermore, the artificial aging of ink samples with xenon light and heat was alsoperformed. Results While the amount of BB7 continuously decreased, its de-ethyl products, E4 and E3, reached their maximumsuccessively; E2, E1, and E0 kept increasing during three months. The aging curves of BB7 and its degraded products underlight exposure in most tested ink entries were best fitted to exponential and quadratic functions, respectively. Conclusion It wasdetermined that the relative amount of BB7 is an exponential function of light energy, and those of E4 and E3 are quadratic ones.The aging process of BB7 is ink formula dependent, and temperature has very limited influence on BB7’s degradation.