高场不对称波形离子迁移谱分离检测3种二甲苯同分异构体

Simultaneous Detection of o-, m-, p-Xylene by High-field Asymmetric Waveform Ion Mobility Spectrometry

二甲苯的3种同分异构体邻二甲苯、间二甲苯和对二甲苯的分离和同时检测难度极大。本研究采用自制的真空紫外光电离源高场不对称波形离子迁移谱仪,提出了"指纹特征获取-分离参数选择-异构体实验分析"的同分异构体检测方法,进行了邻二甲苯、间二甲苯、对二甲苯3种同分异构体同时检测的研究。在二甲苯异构体指纹谱图分析的基础上,提取了邻、间、对二甲苯的特征离子峰,基于分离电压幅值-峰位置关系分析,以及谱图叠加的方法,确定了最佳分离条件为分离电压700 V、载气流量400 L/h。在此条件下,得到邻、间、对二甲苯特征离子峰峰位置分别为4.36、14.96和11.16 V,保持了较大的间距,同时与二甲苯混合物检测谱图中峰位置为4.33、14.71和11.25 V的离子峰保持了良好的一一对应关系,误差仅为0.03、0.25和0.09 V。采用本方法实现了二甲苯混合物的同时分离检测,验证了方法的准确性。在保留特征离子峰的前提下,间二甲苯检出限为0.047 mg/m^3,低于国家标准GB/T 18883-2002规定的二甲苯室内空气检出量0.20 mg/m^3,线性范围为0.24～2.40 mg/m^3。本研究为二甲苯异构体的检测提供了技术支持,同时为UV-FAIMS对同分异构体的快速、高精度检测提供了参考方法。

A novel simultaneous detection method for isomers by spectrometry feature acquisition-separation parameter optimization-isomer analysis was proposed and verified. Dependent on self-made UV-FAIMS instrument, we investigated the separation of o-, m-, p-xylene by high-field asymmetric waveform ion mobility spectrometry(FAIMS). By analyzing the spectrometry feature of xylene isomers, the characteristic peaks of o-, m-and p-xylene were extracted;by analyzing the relationship between dispersion voltage and characteristic peak position, the best separation voltage range was determined to be 550-800 V, and by further analyzing of superimposing spectrometry, the best separation voltage was found to be 700 V under the carrier gas flow rate to be 400 L/h. Under this experimental condition, the peak positions of o-, m-, p-xylene characteristic ions were 4.36, 14.96 and 11.16 V, which kept a great spacing and maintained a fairly good one-to-one correspondence to xylene mixture detection spectrometry(Peak positions: 4.33, 14.71 and 11.25 V) with errors of only 0.03, 0.25 and 0.09 V. The experiment realized the simultaneous separation and detection of the xylene mixture, and the result verified the correctness of the isomer detection method. Under the premise of retaining the characteristic peak, the detection limit of m-xylene was 0.047 mg/m^3, which was less than the indoor air detection amount of 0.20 mg/m^3 specified in the national standard GB/T 18883-2002, and the linear range was 0.24-2.4 mg/m^3. This study provided technical support for the detection of xylene isomers, and provided a methodological basis for the rapid and high-precision detection of isomers by UV-FAIMS.