Real-time monitoring of the work environment using ion-mobility spectrometry

• Published in: Environmental and Occupational Health Practice Vol. 6; no. 1; p. 2023-0025-OA
• Main Authors: Takaya, Kazunari, Shibata, Nobuyuki, Hagiwara, Masayoshi, Takaya, Mitsutoshi, Matoba, Shiro
• Format: Journal Article
• Language: English
• Published: Japan Society for Occupational Health 2024
• Subjects: arrival-time shift; ion-mobility spectrometry; real-time monitoring
• ISSN: 2434-4931; 2434-4931
• DOI: 10.1539/eohp.2023-0025-OA

Objectives: 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. Methods: 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. Results: 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%. Conclusions: 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.