Highly Sensitive Detection of Polystyrene by On-line Splitless Pyrolysis-Gas Chromatography/Mass Spectrometry with Cryo-Trapping of Pyrolyzates and Forced Venting of Carrier Gas
Highly Sensitive Detection of Polystyrene by On-line Splitless Pyrolysis-Gas Chromatography/Mass Spectrometry with Cryo-Trapping of Pyrolyzates and Forced Venting of Carrier Gas
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DOI：
10.1016/j.jaap.2022.105707
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发表时间：
2022-09
影响因子：
6
通讯作者：
Koji Tei;Mai Matsueda;K. Matsui;T. Ishimura;A. Watanabe;W. Pipkin;N. Teramae;H. Ohtani;C. Watanabe
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文献类型：
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作者：
Koji Tei;Mai Matsueda;K. Matsui;T. Ishimura;A. Watanabe;W. Pipkin;N. Teramae;H. Ohtani;C. Watanabe
热解气相色谱/质谱 (Py-GC/MS) 已被广泛用作聚合物分析的强大工具。在 Py-GC/MS 测量中，GC 方法通常采用分流进样条件进行定性和定量分析，但据报道，将热解产物不分流注入 GC/MS 可以获得对少量分析物更高的灵敏度，因为分流比与进入检测系统的分析物量成反比。然而，不分流进样的总载气流速较慢，需要将柱流速保持在几毫升/分钟左右，这会增加在热解室中的停留时间，从而导致热解产物在热解器中发生分解和重组等不利的副反应。在本研究中，我们开发了一种新的在线不分流 Py-GC/MS 方法，称为强制排气和捕集不分流 (F-Splitless) 方法，该方法基于热解产物的低温捕集和高载气流速下载气的强制排气。使用苯乙烯单体和三聚体作为关键化合物，通过 F-不分流方法测量聚苯乙烯 (PS) 的校准曲线，在 0.01 ng 至 100 ng 的浓度范围内显示出良好的线性。基于 LOD：3σ/a 和 LOQ：10σ/a 的标准，苯乙烯单体 (S) 的检测限 (LOD) 和定量限 (LOQ) 分别为 17 pg 和 56 pg，其中校准曲线的斜率和 σ 是使用选择离子监测 (SIM) 模式的最小浓度峰面积的标准偏差。在微量 PS 浓度水平下，可以识别出来自环境的污染。然而，100 pg 的 PS 在 SIM 模式下显示 S 的信噪比 (S/N) 为 570，并且可以根据基于信噪比 (S/N) 的 LOQ 标准对 1.8 pg 的 PS 进行定量，即 S/N = 10。
Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has been extensively used as a powerful tool for polymer analysis. In Py-GC/MS measurements, GC methods have usually employed split injection conditions for qualitative and quantitative analysis, but splitless injection of pyrolyzates to GC/MS has been reported to obtain higher sensitivity for small amount of analytes, since split ratio is inversely related to the amount of analyte entering the detection systems. However, the slower total carrier gas flow rate of splitless injection, which is necessary to keep the column flow rate at around a few mL/min, can increase residence time in the pyrolysis chamber, which can cause unfavorable secondary reactions of pyrolyzates such as decomposition and recombination in the pyrolyzer. In this study, we developed a new on-line splitless Py-GC/MS method called the Forced-Venting-and-Trap-Splitless (F-Splitless) method, based on cryo-trapping of pyrolyzates and forced venting of carrier gas under high carrier gas flow rate. Calibration curves measured by the F-Splitless method for polystyrene (PS) using the styrene monomer and trimer as key compounds show a good linearity over the concentration range from 0.01 ng to 100 ng. Limit of detection (LOD) and limit of quantification (LOQ) were 17 pg and 56 pg for the styrene monomer (S) based on the criterion of LOD: 3σ/aand LOQ: 10σ/a, whereais the slope of the calibration curve and σ is the standard deviation of the peak area of the minimum concentration, using the selected ion monitoring (SIM) mode. At a trace concentration level of PS, contamination from the environment was recognized. However, 100 pg of PS showed a signal to noise ratio (S/N) of 570 for S in SIM mode and 1.8 pg of PS could be quantified according to the criterion of LOQ based on signal to noise ratio (S/N), i.e., S/N = 10.