Oxidant Canister Cleaning in Preparation for Sampling and Analyzing Airborne Ethylene Oxide and Other VOCs

Volatile organic compounds (VOCs) such as ethylene oxide (EtO) grow with time in the blank levels of canisters used to sample, store, and analyze said compounds despite cleaning with the current state-of-the-art methods. This problem has existed for the air measurement and monitoring community since the inception of air sampling with canisters in the early 1980s. It has been postulated that this growth is due to the oxidative degradation of canister residues containing higher-molecular-weight compounds and/or particulate matter (PM). The current manuscript describes the use of hydrogen peroxide (H₂O₂) for the effective removal of EtO, other VOCs, and/or their presumed precursors while leaving inert residuals. Results demonstrate that 10 heavily contaminated canisters, subjected to a 7 day zero-air verification, had EtO concentrations averaging 7.50 ppb_v and 47 ppt_v for traditional and proposed oxidant cleaning methods, respectively. Results also demonstrate that 19 of 20 lightly contaminated canisters with EtO concentrations above 20 ppt_v, despite traditional cleaning, had been reduced to nondetectable levels with the recommended oxidant canister cleaning approach. In addition, these 19 canisters passed a 7 day known-standard verification of 150 ppt_v to confirm that there were no biases associated with the proposed oxidant cleaning method. The heavily and lightly contaminated canisters were evaluated for cleanliness and recoveries using U.S. EPA Method TO-15 and Draft Method 327, respectively. The oxidant cleaning method, results, discussion, and opportunities for future work are addressed in the current manuscript.