应用高效液相色谱法从其字迹鉴别蓝黑墨水的种类及其在字迹中的人工老化规律

Distinguishing Different Kinds of Blue-Black Ink from Handwriting and the Regularity of Artificial Aging of the Ink Used in Handwriting by HPLC

分别用须作鉴别的蓝黑墨水样品及用酸性墨水蓝及直接湖蓝5B两种染料配成的标准溶液(上述两种染料为配制蓝黑墨水常用的原料)在准备好的纸上画出几组平行直线。分别剪取长度为1cm的上述带有字迹的纸,加入提取剂(甲醇、水及冰乙酸以50比50比0.5的体积比混合)0.1mL,室温下提取10min,取提取液10μL进样,进行高效液相色谱分析。用C18色谱柱,流动相为甲醇与0.08mol.L-1四丁基氢氧化铵溶液以50比50体积比混合的溶液,按反相离子对色谱法进行分离及测定,根据结果对墨水的种类作出鉴别。另对墨水字迹进行加热,紫外灯照射及自然光照射等方法作人工老化处理,得到了相应处理条件下字迹的墨水相中相关染料的相对含量的变化规律,为蓝黑墨水字迹形成时间的鉴定提供了科学依据。

Several sets of parallel straight lines were drawn on sampling papers separately with the blue-black ink samples and the standard dye solutions prepared individually from acid ink blue G and direct sky blue 5B, which are the dyes used commonly for preparation of the blue-black ink. A portion of 1 cm in length was cut from the paper with the writing, and the ink on the paper was extracted with 0. 1 mL of extraction agent （a mixture of methanol, H2O and glacial acetic acid mixed in the ratio of 50 to 50 to 0. 5 by volume）. An aliquot of 10 μL was taken and introduced into the instrument for HPLC analysis. C18 chromatographic column and mobile phase solution containing methanol and 0.08 mol·L-1 tetrabutylammonium hydroxide solution （mixed in the ratio of 50 to 50 by volume） were used in the reverse phase-ion-pair chromatographic separation. Based on the results of HPLC analysis, kind of the blue-black ink was identified. Artificial aging treatments of the ink-writing were performed by methods of heating and irradiation with ultra violet light or with natural light, and laws of the change in relative contents of the respective dyes under various aging treatments were found, which furnished the scientific basis for the determination of time of formation of the writing.