ethylene oxide measurement research update
TRANSCRIPT
Ethylene Oxide Measurement Research
Update
State/USEPA Region 5 Air Toxics Risk Assessment
Meeting
November 12, 2019
Ned Shappley
Office of Air Quality Planning
and StandardsAir Quality Assessment Division
1
Center of Environmental Measurement and
Modeling
Tiffany Yelverton
Office of Research and
Development
2
AmbientNear-SourceSource
Measurement
Ethylene Oxide Basics
and Background
Agenda
Ethylene Oxide
3
• Chemical/Physical Properties
• Molecular weight: 44.053 g-mol
• Boiling point: 10.4C (51F)
• Water soluble
• Vapor pressure : 1.46 atm @ 20C
• Flash point : 20C (−4F)
• Half-life in atmosphere (38 to 382 days)
• Hazards
• Extremely flammable
• Irritant
• Mutagen
• Listed as a carcinogen
Production and
Usage (Industry
Slide)
4
5
Sensitivity Fit-for purpose
Ease of use Economically viable
Ideal Measurement Approach
EtO Measurement Challenges • Legacy methods are no longer sensitive enough to measure at the
concentrations needed to demonstrate compliance with some emission
standards .
• Ambient concentration for air toxics in the low ppt range has not been well
studied.
• Use of measurements to assist in
meaningful emission reductions.
• Measurement Push:
• Improve sensitivity
• Identify emission sources
• Quantification from non-traditional
emission points
• Real-time measurements
• Cost-effectiveness
Ethylene Oxide Regulations – Air Emissions
6
• Ethylene Oxide 1 of 187 regulated air toxics (Major and Area Sources)
• Active Rulemaking : Commercial sterilizers (O) and Miscellaneous Organic Chemical Manufacturing (FFFF)
• Other rules: Hazardous Organic NESHAP (F-H), Polyether Polyols Production (PPP), Hospital Sterilizers (WWWWWW), and more..
• Current Federal Emission Standards: Removal efficiencies (NA - 99%) or concentration value (1 – 20 ppmv)
• Future Federal Emission Standards: Removal efficiencies (99% - 99.99%) or concentration value (< 1 ppmv?)
National Emission Standards for Hazardous Air Pollutants (Major and Area Sources)
• Removal Efficiencies as low as >99.9 and concentration values of as low as < 0.2 ppmv
• Installation of Continuous Emission Measurement Systems (CEMS)
• Design Criteria (e.g., Method 204) and continuous monitoring for verification
State Air Toxic Rules
Ongoing Foundational Work
7
• No NIST Standard Reference Material (SRM) available
• Stability of and accuracy evaluation, of manufacturer “certified” standards
• Three months into a twelve months evaluation
• 5 vendors
• 4 ranges (100 ppbv to 100 ppmv)
• Alternative to NIST SRMs, EPA ALT-114 and ALT-118
Evaluation of commercially available calibration gas cylinder standards
• Analytical sensitivity vs. sample transport/sample recovery
• Sample material
• Sample temperature
Sample transport
Source Emission Measurements
8
• Appropriate techniques for existing emission standards
• Sensitivity concerns (all)
• Interference concerns (all)
• Method DQOs are not appropriate for low concentration measurements
Existing - Method 18 (GC-detector), Method 320 (FTIR),
and Method 25A (THC surrogate measurements)
• Near and Mid-IR optical spectroscopy approaches
• Better specificity
• Better sensitivity
• Good time resolution
RESEARCH:
New real-time techniques being evaluated
• Derivatization techniques
• Collection and concentration in an impinger train (Standard Method 5)
• Standard GC/ECD analytical finish
• Improved sample collection (isokinetic sampling) and theoretical sensitivity
RESEARCH:
Repurposed techniques (wet-impinger approach)
Wet impinger method
9
1.0 N HCl in
n-propanol
C2H5BrO + CH3CH(OH)CH3
HBr · CH3CH(OH)CH3C2H4O +
This Photo by Unknown Author is licensed under CC BY-SA
Mid and Near IR
Spectroscopy
Applications of Absorption Spectroscopy Using Quantum Cascade Lasers - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/HITRAN-simulation-of-absorption-
spectra-for-major-atmospheric-species-Color-figure_fig1_265856964 [accessed 3 Nov, 2019]
Optical techniques being developed and evaluated
11
BAND–PASS FILTER FTIR
- Commercially Available
- CEMS Application
- Method 320 compliant ???
- Source and near source application
- Detection limit 5 – 20 ppb @ 15 seconds
CAVITY RINGDOWN
- Mature technology
- Not commercially available (6- 12 months)
- Source and near source application
- Theoretical Detection Limit < 1 ppb @ 1 second
QUANTUM CASCADE LASER
- Specificity
- Not a commercial instrument
- Near source and ambient application
- Theoretical detection limit 100 ppt @ 60 seconds to 300 ppt @ 1 second
INTERBAND CASCADE LASER
- Commercially available
- Lower cost
- Near source applications
- Detection Limit < 1 ppb @ 30 second
MORE
Stationary Source Emission Measurements Products
12
New Performance Specification for oHAPs (CEMS)
- Performance Based approach for CEMS
- Possible Proposal Spring/Summer 2020 with commercial sterilizer rule
Other Test Method – Wet Impinger Approach (Possible)
- Draft Other Test Method, Summer 2020
- Method 301 validation field evaluation, Fall 2020/Spring 2021
- Possible Proposal Summer/Fall 2021 as Reference Method
New Optical Source Reference Method
- Performance Based Approach
- Self-validating method
- Possible Proposal Winter 2020/Spring 2021
Near-Source Measurements
13
Regulated fugitive emissions
• Leaks from valves, pumps, seals, and connectors
• Subject to LDAR program
• EPA Method 21 (FID or PID*)
• Threshold for leak repair @ 500 ppm to 10,000 ppm
• Limitations
• Instrumentation is not specific to EtO
• Periodic in nature
• Difficult to correlate a concentration to a mass emission.
Unregulated fugitive emissions
• Uncontrolled emissions leaving a building
• Atmospheric coolers, cooling towers, and holding tanks
• How do you measure/monitor?
Advanced and Emerging
Screening Techniques
• Area Leak Monitoring
– Utilization of existing monitors or emerging sensor technology
– Continuous monitoring for leaks
– Quick identification and repairs of leakage components
• Geospatial mapping of air pollutants (GMAP) vehicles
– Other Test Method - 33A
– Precise global positioning system and compact weather stations
– Fast-response Instruments
– Applications: fenceline and hot spot
14
Active Sorbent Trap Options (Fenceline)
15
• Refine procedures to improve sensitivity
• Longer deployment (a la Method 325A)
Build off the NIOSH/OSHA EtO sorbent trap methods
• EtO adsorbed on brominated carbon trap (ANASORB 747)
• Derivatizes it to stable 2-bromoethanol
Derivatization methodology
• Active sampling
• Trap design to allow for larger sample volume
• Alternative analytical technique to improve sensitivity
Evaluate
Near – Source Emission Measurements Products
16
Area Monitoring
- Bench evaluation of instrumentation Spring/Summer 2020
- Look for industry partner to evaluate for alternative fugitive monitoring approach Fall/Winter 2020
Mobile Platform Measurements
- Bench evaluation of instrumentation Spring/Summer 2020
- Possible field trials Fall 2020
- Draft procedures and guidelines (Winter 2020/Spring 2021)
Passive/Active Sorbent Approach
- Draft Other Test Method Winter 2020
- Method 301 validation field evaluation, Spring 2021/Summer 2021
- Proposal Winter 2021
Ambient Measurements
17
Improvement of Existing Methodology
• Leaks from valves, pumps, seals, and connectors
• Subject to LDAR program
• EPA Method 21 (FID or PID*)
• Threshold for leak repair @ 500 ppm to 10,000 ppm
• Limitations
• Instrumentation is not specific to EtO
• Periodic in nature
• Difficult to correlate a concentration to a mass emission.
Emerging and Innovative Techniques
• RARE Grant
• Additional Evaluation of Optical Techniques
• How low can we go?
Ambient Measurement
EPA Compendium Method TO-15 for Air Toxics
• Specially lined evacuated stainless-steel canisters (i.e., SUMMA or silica coated)
• Pre-concentration on a sorbent which is thermally desorbed and seperated and analyzed via GC/MS
• Proven detection limit* (SIM mode) of ~0.08 ug/m3 (~50 ppt)
• Limitations
– Interference with coeluting compounds
– Leadtime between sampling and analysis
– Sensitivity and Cost Concerns18
19
EtO GC/MS Basics
TO-15 Improvements for EtO
20
EtO measurements can be achieved by typical TO-15 set-up, with
limitation
• MDL not as low as desired even with selective ion monitoring
• Retention time shifts and tailing on typical non-polar columns
• Lower MDL and consistent retention time could be achieved by a polar column but effects performance for a few low MW air toxic analytes
Issues with abundant ions for quant.
• Ion 29 co-elutions (e.g., trans-2-butane)
• Monitor addition ions to aid EtO identification (41 and 56)
• Use of Ion 44 – CO2 and water management
• Leak Checks
• Optimization
• Data Review and validation
Innovative Ambient Approach
21
• EPA Office of Research and Development
• EPA Office of Air Quality Planning and Standards
• EPA Regions 5 and 6
US EPA Regional Applied Research Effort (RARE) grant
• Advanced sorbent sampling approach paired with optimized optical measurement approach(es)
• Goal : Single ppt detection limit
• Semi-continuous application
• Application to other air toxics
2 year grant to develop and deploy novel ambient/near-source measurement technology
Ongoing Measurement Efforts
22
23
Ethylene Oxide Concentrations
October 1, 2018 – March 31, 2019
Investigating the Distribution of EtO data Across the U.S.
24
• EPA has worked with the national air toxics
contract lab to analyze EtO concentrations
at a subset of the NATTS and UATMP sites
for the 4thQ 2018 – 1st Q 2019 period
• Outreach calls have been completed with
the affected states, and the data are in final
QA review prior to rollout/AQS posting
• The average concentration for this data set
is 0.297 μg/m3
• There is a statistical difference (lower)
between a grouping of [GLKY, LAWA,
SEWA] and the other sites
For Internal EPA Use
Only
Questions ?
25