Insights from industry

The Advantages of Monitoring Ethylene Oxide with OE-FTIR

insights from industryKelly McPartlandApplications ManagerThermo Fisher Scientific 

In this interview, AZoM spoke with Kelly McParland of Thermo Fisher Scientific to discuss the importance of ethylene oxide monitoring and how Thermo Fisher’s EMS-10 emissions monitoring system and MAX-IR FTIR gas analyzer helps streamline the process.

Please could you introduce yourself and your role at Thermo Fisher Scientific?

My name is Kelly McPartland, and I am the Senior Applications Manager for Gas Analysis Solutions at Thermo Fisher Scientific. I have been working with FTIR gas analysis since 2015, and for the past three years, I have been doing a lot of work with ethylene oxide (EtO) source emissions monitoring.

What is FTIR, and why is it important in gas analysis?

FTIR stands for Fourier transform infrared and is one of, if not the most common form of infrared spectroscopy. Fourier transform infrared spectrometers were first developed for commercial use in the 1960s, primarily employed in advanced research applications due to the instrument costs and the large computers required to operate them.

The technology has evolved reducing costs and improving general FTIR capabilities; FTIR spectroscopy is now considered the standard for organic compound identification work in academic, analytical, QC/QA, and forensics laboratories. FTIR technology is able to meet the challenges of in-line processes, batch sampling, gas purity/certification, emissions testing, and ambient air monitoring applications, and the recent introduction of optically enhanced FTIR (OE-FTIR) enables the technology to be used in gas analysis when very low detection limits are required.

What advantages does the introduction of FTIR-based continuous emissions monitoring (CEM) give you?

There are a  number of advantages to FTIR-based CEM systems over other techniques, most notably gas chromatography (GC). One is speed - with GC-based techniques, you are doing batch sampling, which delays the response time and gives you fewer data points. With an extractive FTIR-based CEM, there is a continuous flow through the gas cell, and the sample is constantly probed with the IR beam. Therefore more process information and data points can be gathered, and again, it has a fast response time.

The Thermo Scientific EMS-10 is a four-channel CEM system capable of measuring a single sample channel in about 30 seconds, or if you were just sitting on a single channel and monitoring one stack, the typical data collection rate is once a minute.

The other main advantage of the EMS-10 system is its sensitivity. It encompasses the Thermo Scientific MAX-IR FTIR Gas Analyzer with Thermo Scientific StarBoost Optical Enhancement Technology; this is the OE-FTIR technology I referred to earlier. The StarBoost technology dramatically enhances the sensitivity of the FTIR analyzer and allows users to achieve detection limits that are competitive with GC mass spectrometry (GC-MS) techniques, yet the results can be obtained in real-time.

Then there is selectivity. With GC-based techniques, you are susceptible to misidentification from coelluting peaks. EtO is challenging because its molecular weight is the same as propane, acetaldehyde, CO2, and that can cause coellution and misidentification of EtO.

Another key advantage is stability. We use a novel zeroing technique with the Thermo ScientificMAX-OXT thermal oxidizer module, which eliminates biases from interferences. We can also use a special data acquisition technique, called Auto Reference, to eliminate baseline drift. The calibration drift on the FTIR analyzer is minimal, and it is factory calibrated. It ships with a quantitative library including a resident EtO calibration, and the user will never need to recalibrate in the field. The facility will use that one calibration for the entire lifetime of the instrument.

Finally, the robustness of the technique is another major advantage. There is minimal maintenance with this system, and it has a very long lifetime. The spectrometer in the MAX-iR FTIR gas analyzer has a mean lifetime of 10 years before failure.

Moreover, the analyzer also has a very low cost of ownership. Typically, it can run continuously for years. However, we recommend a yearly preventative maintenance visit where you might clean the gas cell, check the signal and other diagnostics, and then change the diaphragm on the pump.

Why is monitoring ethylene oxide (EtO) a good example of the MAX-iR analyzer’s capabilities?

Video credit: Thermo Fisher Scientific

EtO is both carcinogenic and mutagenic. It is commonly used in the chemical industry to sterilize medical instruments and as a reaction intermediate in the production of ethylene glycol. It is used frequently by industries in North America and globally in places like Japan and Germany. It is also one of the most difficult gases to analyze due to it being extremely reactive. This makes it difficult to transport EtO samples from the stack to the analyzer.

When combined with  StarBoost optical technology, the MAX-iR FTIR Gas Analyzer enables users to achieve single-digit ppb to 10’s of ppt detection limits while ensuring all of the benefits of real-time FTIR analysis are preserved. This breakthrough is only available with the MAX-iR analyzer and eliminates the need for costly methods such as MS, GC or cavity ringdown spectroscopy (CRDS) across a diverse range of applications.

Aside from EtO trace analysis, the MAX-iR analyzer is also capable of analyzing hundreds of other gases, making it an ideal tool in terms of trace analysis.

Why is it important to measure ethylene oxide in the environment?

Ethylene oxide has been measured in the air at low levels in many areas of the United States. While the majority of these areas were close to industrial plants, some were not. It is considered that those working in or living near industrial facilities that release EtO are like to be exposed to greater levels of the gas.

EtO has been identified as a known human carcinogen, and the US Environmental Protection Agency (EPA) has determined that prolonged occupational exposure and inhalation of EtO can induce a carcinogenic response. Furthermore, recent studies suggest that the toxicity could be greater than previously thought, which means there is a real impetuous to detect EtO at levels as low as possible in real-time.

How are ethylene oxide source emissions typically measured?

Due to its toxicity, there is a huge interest in monitoring EtO at very low levels in and around the aforementioned industrial facilities in the US. EtO emissions monitoring gained a lot of interest after a National Air Toxics Assessment (NATA) conducted in 2014 was published by the EPA in 2018. Since then, the US EPA has been working on new proposed emission standards for EtO.

Historically, ethylene oxide source measurements have been performed annually in the US in line with the EPA Method 18. That may involve collecting a sample in the field and then shipping that sample back to a laboratory for analysis. This offline technique is not ideal because the site often has to wait a very long time to get results. Making this measurement with FTIR grants the user access to results in real time.

What are the challenges you need to address when monitoring ethylene oxide at ultra-low levels using FTIR?

The first major challenge is the transportation of this gas at parts-per-billion (ppb) levels because it is highly reactive. When monitoring ppb levels, instrument sensitivity becomes very important.

With any optical technique, including FTIR, managing your interferences is important. There could be very high moisture, CO2, and other atmospheric interferences, and it is critical to develop a method such that the ethylene oxide measurement is not biased by interfering gases. When taking all these factors into account, it is important to develop and meet QA/QC requirements, especially if the measurements will be used for compliance.

Additionally, ease of use is very important for emissions monitoring. If the analyzer is online 24/7, everything should be fully automated, and users should be able to easily integrate it with the factory data collection system.

When it comes to EtO monitoring, the selection of materials is important, both in terms of the sample line and the calibration line. For the sample line, we have had success with PTFE line, which has to be heat traced to maintain the gas at the same sample temperature as the stack.

You have mentioned sample transport as a challenge. How do you assess and track this?

We assess sample transport by performing a dynamic spike recovery. This test involves diluting an EtO calibration standard in stack emissions at a ratio of 10:1, and it challenges the entire sampling train. It is important to use EtO rather than a surrogate.

Our metric for quality for this test is that the EtO recovery must be within 70-130% of the expected result. Most of the time, it is much better than that.

When we perform the spike test, we will assess the response time to ensure we are turning over the gas cell fast enough and getting results in an efficient amount of time. Typically, the gas is equilibrated after turning the gas cell over five times due to gas mixing. We measure response time twice, both the rise and fall times.

What is the main value for a customer considering the MAX-OXT Thermal Oxidizer Module?      

The MAX-OXT module is very helpful at getting extremely good spectral subtraction; it serves as a way to validate your results and improves the quality of the data that is being collected. You are not inherently increasing the sensitivity of the FTIR analyzer, but it makes the analysis a lot more robust and defensible for trace applications.

We’ve demonstrated how robust trace measurements are with the MAX-OXT module by performing long term drift assessments. Two drift assessments are performed when the analyzer is first installed - a zero drift assessment and a calibration drift assessment. The zero drift assessment is done with zero gas. We do that once a day around the same time each day for seven days.

All the data we need is then collected using the EMS-10system, which is a fully automated, four-channel CEM system. Essentially, we have a configuration that is optimized for very low-level detection of EtO.

About Kelly McPartland 

Kelly McPartland is an Applications Manager with Thermo Fisher Scientific, Gas Analysis Solutions. A graduate of Boston University, Kelly is an expert in FTIR gas analysis, associated method development and data validation. As a senior-level technical liaison for gas analysis customers, Kelly has been a key architect and manager for data acquisition gas analysis software, ensuring quality results and customer usability. Kelly also works closely with state and federal regulatory agencies to develop Quality Assurance Plans and test methods for new technologies.

Kelly’s expertise in FTIR gas analysis, which spans hardware systems to method development and data validation, stems from her liaison work with customers as well as regulatory agencies.

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Materials & Structural Analysis.

For more information on this source, please visit Thermo Fisher Scientific – Materials & Structural Analysis.

Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.


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