Takaya Kazunari, Shibata Nobuyuki, Hagiwara Masayoshi, Takaya Mitsutoshi, Matoba Shiro
National Institute of Occupational Safety and Health, Kawasaki, Japan.
High Energy Accelerator Research Organization, KEK, Ibaraki, Japan.
Environ Occup Health Pract. 2024 Jun 5;6(1). doi: 10.1539/eohp.2023-0025-OA. eCollection 2024.
Ion-mobility spectrometry (IMS) is a promising system for on-site real-time monitoring of volatile organic compounds (VOCs). Calibration curves derived from shifts in nominal arrival-time spectra of chemical substances relative to those of water clusters enable quantitative analysis at high concentrations.
This study investigated the adaptability of IMS to real-time monitoring of VOCs in the work environment, using toluene as a test case. Toluene concentrations were measured by IMS at one-minute intervals during a ten-minute simulated cleaning operation.
The arrival-time shift was lower at high concentrations because ion production saturates as the toluene concentration approaches the limit of ionizability, with a resulting decrease in slope of the calibration curve. The lower limit of quantification for toluene was assumed to be 13.3 ppm because no arrival-time shift was observed at lower concentrations. The time-averaged toluene concentration measured by IMS for 10 minutes of operation was 45.8 ppm, which is comparable to that measured by gas chromatography-mass spectrometry (GC-MS; 44.3 ppm) within ~3%.
Our results indicate that the measurement of toluene concentrations is possible at one-minute intervals by IMS, making it possible to track rapid changes in workplace conditions. Therefore, IMS can measure exposure to VOCs in real-time with an accuracy similar to that of GC-MS.
离子迁移谱（IMS）是一种很有前景的用于现场实时监测挥发性有机化合物（VOC）的系统。由化学物质相对于水团簇的标称到达时间谱的偏移得出的校准曲线能够实现高浓度下的定量分析。
本研究以甲苯为例，调查了离子迁移谱用于实时监测工作环境中挥发性有机化合物的适用性。在10分钟的模拟清洁操作过程中，每隔1分钟用离子迁移谱测量一次甲苯浓度。
在高浓度下到达时间偏移较小，因为随着甲苯浓度接近电离极限，离子产生达到饱和，导致校准曲线斜率下降。由于在较低浓度下未观察到到达时间偏移，因此甲苯的定量下限假定为13.3 ppm。在10分钟的操作过程中，离子迁移谱测量的甲苯时间平均浓度为45.8 ppm，与气相色谱 - 质谱联用仪（GC - MS；44.3 ppm）测量的结果相当，误差在约3%以内。
我们的结果表明，离子迁移谱能够每隔1分钟测量甲苯浓度，从而能够追踪工作场所条件的快速变化。因此，离子迁移谱可以实时测量挥发性有机化合物的暴露情况，其准确度与气相色谱 - 质谱联用仪相似。
