Real-Time Measurement of EPA Regulated HON Compounds and Environmental Pollutants Using SIFT-MS

New Environmental Protection Agency (EPA) regulations for the HON (Hazardous Organic NESHAP) compounds mandate that alternative monitoring methods, like Selected Ion Flow-Tube Mass Spectrometry (SIFT-MS), achieve method detection limits (MDLs) at least one-third of the action level for compounds such as ethylene oxide (EtO), chloroprene, benzene, 1,3-butadiene, ethylene dichloride, and vinyl chloride. Accurately measuring these hazardous compounds relative to their defined action levels is important when determining what regulatory or remedial actions may be necessary to protect public health and the environment. All MDL data was collected using a one-minute single-compound method. The MDLs presented here demonstrate that all HON compounds can be measured at one-third of their respective action level. At Syft, methods are regularly optimized to enhance performance. However, only the EtO method was specifically adjusted due to interference from acetaldehyde. The method involved acetaldehyde subtraction using NO+. Extending the duration of the monitoring method proportionally improves the MDL, with the EtO MDL currently falling below the action level at over 30 minutes and reaching one-third of the action level at approximately 3 hours. This is significantly shorter than the 24-hour standard canister method, enabling multiple high-precision samples within a day and thus improving temporal resolution and source identification. Vinyl chloride and ethylene dichloride can be distinguished and quantified selectively using their differing reactivity with H3O+ and O2+ ions. The EPA MDL estimation procedure, supported by low concentration calibrations, confirms the realism and attainability of the MDLs. This is exemplified by the excellent linearity in 1,3-butadiene measurements down to low part per trillion by volume (pptV) concentrations. The combined results demonstrate the unique speed, selectivity, and sensitivity of SIFT-MS for environmental monitoring applications.