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    新型含氟基质在基质辅助激光解析电离飞行时间质谱法测定全氟磺酸中的应用

    Application of New Fuorine-Containing Matrix in the Determination of Perfluorosulfonic Acids by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry

    • 摘要: 基于Witting反应,制备了可用于酸性小分子分析的新型基质1,1-二(3-氟苯基)乙烯(EDF),并通过核磁共振和质谱确认了EDF的结构。首先取适量EDF溶于二氯甲烷中,涡旋振荡5 min,配制成1 g·L-1的EDF基质溶液;将食品级包装材料汉堡包装纸剪成0.5 cm×0.5 cm的碎片,取100.00 mg在5 mL甲醇中室温超声提取2 h,过0.22 μm滤膜,得到待测样品溶液。然后采用逐层点样的方法,移取0.6 μL的EDF基质溶液快速点在不锈钢靶板圆点处,以二氯甲烷为溶剂的EDF基质溶液迅速挥干,因其沸点低以及移取的量少,正好覆盖圆点的范围,再移取0.8 μL待测样品溶液点在不锈钢靶板的相同位置,待其自然挥干后,进行基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)分析,并对比了EDF与常用基质9-氨基吖啶(9-AA)、α-氰基-4-羟基肉桂酸(CHCA)以及1,6-二苯基-1,3,5-己三烯(DPH)对全氟辛烷磺酸(PFOS)和全氟丁烷磺酸(PFBS)的检测性能。结果表明,EDF可以达到和上述几种常见基质类似的信号强度,且背景更干净、几乎无基质干扰峰。以EDF为基质,以二十一烷酸为内标,建立的PFOS和PFBS标准曲线的线性范围均为20~250 μg·L-1,检出限(3S/N)均为1 μg·L-1。按标准加入法对实际包装纸样品进行回收试验,回收率为90.3%~108%,测定值的相对标准误差(n=7)在30%以内。说明该EDF基质检测结果较理想,适用于检测包装材料中的全氟磺酸。

       

      Abstract: Based on Witting reaction, a novel matrix 1,1-bis(3-fluorophenyl) ethylene (EDF) was prepared for the analysis of acidic small molecules, and the structure of EDF was confirmed by NMR and MS. A appropriate amount of EDF was dissolved in dichloromethane, following by vortex oscillation for 5 min to prepare 1 g·L-1 EDF matrix solution. The hamburger wrapping paper of food grade packaging material was cut into 0.5 cm×0.5 cm fragments, and 100.00 mg of fragments were extracted ultrasonically at room temperature for 2 h in 5 mL of methanol. The extract was passed through a 0.22 μm filter membrane to obtain the sample solution to be tested. Layer by layer sampling method was adopted:0.6 μL of EDF matrix solution was transferred to the circular point of stainless steel target plate quickly, and EDF matrix with dichloromethane as solvent evaporated rapidly. Because of its low boiling point and small amount, it just covered the range of circular point. 0.8 μL of the sample solution to be tested was moved to the same position of the stainless steel target plate. After it was evaporated naturally, the sample was analyzed by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). Its detection performance for perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS) were compared with common matrices including 9-aminoacridine (9-AA), α-cyano-4-hydroxycinnamic acid (CHCA) and 1,6-diphenyl-1,3,5-hexatriene (DPH). As shown by the results, EDF could achieve similar signal intensity, but the background was much cleaner without matrix interference peak. Using EDF as matrix and eicosanoic acid as internal standard, the linear ranges of PFOS and PFBS standard curves were both 20-250 μg·L-1, with the same detection limits (3S/N) of 1 μg·L-1. Test for recovery was made on the actual packaging paper sample by standard addition method, giving results in the range of 90.3%-108%, and RSDs (n=7) of the determined values were within 30%. It was shown that EDF matrix had ideal detection results and was suitable for the determination of perfluorosulfonic acids in packaging materials.

       

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