LC—MS／MS法测定蓝色圆珠笔油墨中的碱性染料

目的建立蓝色圆珠笔油墨中碱性染料的LC—MS／MS方法，为蓝色圆珠笔油墨的种类鉴别提供方法。方法用二级质谱寻找并确定结晶紫、甲基紫、维多利亚蓝B、碱性紫14、碱性蓝7和罗丹明B等碱性染料的特征性母离子／子离子对。收集50种蓝色圆珠笔．划线后对其笔道用0．5mm直径打孔器取样，乙腈超声提取。液相分离采用WatersXBridgeC18柱。流动相为0．1％甲酸缓冲液（A）-乙腈（B），梯度程序洗脱。结果4个点的取样量足以满足检测需要，采用相对峰面积的定量方法．结果重现性好．RSD％≤2．3％。应用该方法对50种蓝色圆珠笔油墨中的碱性染料进行检测，区分率为94．4％。结论所建LC—MS／MS方法定性准确，定量可靠，为蓝色圆珠笔油墨的种类鉴别提供了方法。

Determination of Basic Dyes in Blue Ballpoint Pen Ink by Liquid Chromatography Tandem Mass Spectrometry

Objective To establish a method of analysing of basic dyes in blue ballpoint pen ink by liquid chromatography tandem mass spectrometry for the discrimination of blue ballpoint pen ink on a questioned document. Methods Specific precursor and product ion pairs of crystal violet, methyl violet, victoria blue B, basic violet 14, basic blue 7 and rhodamine B were determined by a triple quadrupole tandem mass spectrometer. Ink lines of fifty blue ballpoint pens were drawn on one piece of print paper. Four hole punches of each ink sample were collected with a Harris MICRO-PUNCH （0.5 mm i.d.）. Acetonitrile was added to perform extraction in an ultrasonic water bath. Waters XBridge C18 column was used for separation. Target compounds were eluted by a gradient procedure in which 0.1% formic acid solution and acetonitrile were used as mobile phase. Results Four hole punches of ink samples provided good signals for the analysis. Intra-batch precision was quite good as the relative standard deviation was no more than 2.3%. Discrimination power of established method was 94.4%. Conclusion The present study provided a precise method for the discrimination of blue ballpoint pen ink on a questioned document.