基于HPLC的三芳甲烷类染料字迹人为老化的实验研究

Exploring the Detection of Artificially Aged Writing Based on Analysis of Triaromatic Methane Dye by HPLC

目的对蓝色圆珠笔字迹在经过紫外光源老化后的独特特征进行研究,建立确认紫外灯照射的人为老化文件的方法。方法本文以蓝色圆珠笔字迹为研究对象,蓝色圆珠笔中的三芳甲烷类染料在紫外灯的照射下会吸收光子的能量加速其老化脱甲基的反应,通过适当的假设可以推导出其老化程度随时间变化的老化方程,由于目前紫外灯管几乎全部是线型结构,建立合适的坐标系,假设线型灯管能量分布均匀,且紫外线以球面波的形式传播出去,可以计算出纸面上任意一点的能量,通过纸张表面不同位置的三芳甲烷类染料的老化程度的不同来区别自然老化文件与紫外灯人为老化文件的不同。结果经过实验发现对于紫外灯人为老化文件来说甲基紫初始含量比上老化后含量的对数值与紫外灯对于该点的能量的辐出的比值为一个常数K,该K值稳定,浮动范围小,线性关系的置信度大于99%,可以认为两个参数之间存在显著地线性关系,可以证明对于老化方程的推导和能量密度分布函数的推导合理符合实际,对于自然老化文件来说则不存在这种规律。结论可以利用这种特殊的分布规律构建一个衡量这种分布的函数来定量地确认紫外灯照射的人为老化文件。

Objective Currently the aging file suspected to be made intentionally,albeit difficult to determine,has positive significance in document inspection because a file can be identified as fake once the artificial aging is confirmed when the real written time is different from that of the claimed.Methods We used the writing made with ball-pen blue oil as the research object.Because the tri-aromatic methane dye in ball-pen blue oil will accelerate its aging when exposed to ultraviolet,an aging equation,if founded,can reveal the aging rate of tri-aromatic methane with time elapsing based on some appropriate assumptions.Since almost all the ultraviolet lamps are linear structure and within some distance,for example,a file irradiated intentionally,emit their energy uniformly and transmit the ultraviolet rays spherically,the aging equation can be used to calculate the energy of any point on paper with help of proper coordinates.According to the aging degree of triaromatic methane dye at different position on paper surface,we could verify whether a file was natural aging or artificial with ultraviolet lamp.Results For one point of the file artificially aged with ultraviolet lamp,the content of initial methyl violet,a constituent of tri-aromatic methane dye,was divided by that of post-aging,thus getting a quotient which was converted into a value of natural logarithm;when the value of natural logarithm was further again divided by the value of energy irradiated from ultraviolet lamp on that point,the obtained quotient was a constant（named as K） with small floating range and the degree of linear regression greater than 99%.This could probably prove that our deduction was reasonable and met actuality both for the equation on aging and the function on energy density distribution.However,this law does not exist for natural aging file.Conclusions The artificial aging file with ultraviolet lamp can be quantitatively measured by the function and law we discovered in this study.