Measurement of ethylene oxide with other air toxics from fugitive and area sources

This application note covers the analysis of ethylene oxide as part of an air toxics study in compliance with US EPA Method 327. The note outlines the steps for evaluating method performance and testing system capability, with an emphasis on eliminating the use of liquid cryogen during the analysis. When sampling 500 mL, a method detection limit of 10 ppt was achieved, with a signal-to-noise ratio of 10:1 for the ethylene oxide peak.

Introduction

Ethylene oxide is harmful to human health, and in 2016 was re-categorised as having a 100-in-1-million cancer risk level of 11 ppt.1 This extreme low-level toxicity led to it being incorporated into the list of compounds measured at US EPA National Air Toxics Trends Stations (NATTS) in 2019.2 However, to accurately monitor ethylene oxide, there are many analytical challenges to overcome such as:

• Sampling bias from formation of ethylene oxide in canisters
of all types
• Chromatographic interferents
• Sensitivity due to the molecule’s small size

Monitoring at NATTS sites was a first step towards a broader understanding of the presence of these species in ambient air but it did not address the risks to the public and workers from releases of ethylene oxide at industrial sites.