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Grantee Research Project Results

Final Report: Rapid, part-per-trillion detection of ethylene oxide in ambient air

EPA Contract Number: 68HERC22C0010
Title: Rapid, part-per-trillion detection of ethylene oxide in ambient air
Investigators: Armen, Michael
Small Business: Entanglement Technologies, Inc
EPA Contact: Richards, April
Phase: I
Project Period: December 1, 2021 through May 31, 2022
Project Amount: $99,901
RFA: Small Business Innovation Research (SBIR) Phase I (2022) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Air

Description:

We are developing a rapid Ethylene Oxide (EtO) analysis method capable of delivering method detection limits for EtO in ambient air below 10 part-per-trillion by volume (pptv) with a total cycle time below 5 minutes.  This work focuses on the development of a novel, rapid gas delivery mechanism in the commercially available AROMA-EtO chemical vapor analyzer to preserve the sub-10 pptv method detection limit of that analyzer while reducing cycle time to below 5 minutes.  This project implements a hybrid preconcentration-rapid desorption cavity ring-down spectroscopy (CRDS) system to provide an accelerated EtO analysis.  This initial technology demonstration program has led to the development and successful implementation of this accelerated analysis cycle.  In addition to the gas delivery mechanism developed for this project, a new multi-scale CRDS mode was developed to address the combination of spectral feature widths encountered in the range of molecules (from resolved ro-vibrational modes through high density broad spectral features). This project saw the implementation and testing of these novel methodologies.

Summary/Accomplishments (Outputs/Outcomes):

This project successfully demonstrated a novel, rapid cycle approach to preconcentration and partial background elimination of EtO in realistic ambient matrices.  In the initial phase of this project a method was developed provide well-formed EtO pulses with molecules with significant boiling point separation suppressed by factors exceeding 100x for most compounds. An optimal gas flow pattern was developed to mitigate pulse distorting artifacts due to material affinity providing stable elution pulses. This step also included an initial water removal step. A novel multi-scale mode of CRDS operation was developed and implemented that allows for improved performance in rapidly varying concentrations signals and scenarios with very high concentration dynamic range. The limiting performance of these techniques has not yet been achieved.  Excellent mass linearity was shown in the system down to 50 pptv EtO equivalent concentration with linearity r2=0.99. The accelerated measurement cycle introduced two significant artifacts that have not yet been completely mitigated.  The sample injection and switching introduced very rapid background species, flow, and pressure transients with the CRDS cell.  These transients currently limit the useable performance of the rapid analysis cycle to approximately 1 ppbv EtO and are the subject of ongoing study.

Conclusions:

We have developed and demonstrated a novel, rapid cycle capability for EtO analysis. We have concluded that this is a feasible approach to a part-per trillion EtO analysis; however, we have identified important technical artifacts that interfere with fully realizing the target sensitivity in a compressed analysis time.  In addition, we have demonstrated and validated a new multi-scale CRDS measurement approach that will provide enhanced analytical capabilities across our line of chemical analyzers.

This SBIR project has facilitated the identification of multiple market opportunities and will enhance the capabilities of all AROMA analyzers in the future.  The methodologies developed in this SBIR will be rolled out into our existing ethylene oxide analyzers in the near term, which will enhance their commercial value and reach. During the project period we engaged with multiple customers interested in ambient analysis of ethylene oxide. These customers included federal, state, and local air quality districts, non-profit organizations, community groups, commercial sterilizers, academics, and environmental consultants. We found that these customers are interested in bringing on easily deployable, in-field techniques to measure ethylene oxide below the 100-in-a-million excess cancer risk set by the U.S. EPA. We will continue to engage with the various stakeholders as we work to improve our current measurement techniques for in-field, ambient ethylene oxide analysis.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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Last updated April 28, 2023
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