Industrial Utility Efficiency

Pure Gas Testing-The Benefits of Point of Use Sampling

Pure gases are used frequently across a range of industries: from food and beverage to hospitals, pharmaceutical, and medical device manufacturing. Depending on the usage of the pure gas, different quality standards and acceptable purity limits may apply. Whether the gas is used for purification, extraction, fermentation, or is administered to patients, it is critical that the levels of purity and contamination are acceptable for that particular use. Quality evaluations should be performed at the point of use to understand whether the system is impacting the gas in any way and to ensure the gas is of appropriate purity for its use. Point of use testing for both purity and contamination can be performed by a third-party, accredited laboratory. 


Pure Gas Usage in Industry

Pure gases like nitrogen, oxygen, carbon dioxide are versatile and becoming even more frequently used as technology advances. 

  • Nitrogen helps protect and preserve supplies from oxidation and helps to keep products dry and sterile. “Blanketing with nitrogen” preserves the quality of many food and pharmaceutical products. Oxygen sensitive products require appropriate Nitrogen purity.  Nitrogen is also used extensively in hospitals for cancer and lesion removal, the storage of cells and blood, and for the manufacturing of medicines (CHT, 2020). 
  • Oxygen can be used for fermenting, extending the shelf life of various foods, and as a shield for beef products. It can also prevent the growth of anaerobic bacteria (Inmatec, 2021). In hospital settings, oxygen is used for treating medical conditions such as respiratory arrest, resuscitation, and life support (CHT, 2020). 
  • Carbon Dioxide plays an important role in many food packaging and manufacturing processes. Particularly in beverages, CO2 is responsible for the flavor and freshness of soda, mineral water, and alcoholic drinks. This gas prevents oxidation and slows down fermentation (Rocky Mountain Air Solutions, 2018). 
  • Pure gas mixtures allow users to create modified atmospheric packaging which help ensure the longevity of the products’ lifespan. It can be essential that the right amounts of each gas are in the mixture and free from contamination. 

Because the success of the product and/or treatment depends on the quality of the pure gases, regular monitoring for both purity and contamination is something that should be included in every users’ protocol. Point of use testing helps ensure that maintenance procedures, system dryers, and filtration devices are adequate and appropriate. Pure gases are generally used in high-risk / essential functions and regular point of use monitoring provides confidence that the pure gas is not negatively impacting the product or consumer. 


Gaseous Contamination and Purity

It's important to understand the difference between gas purity and gaseous contamination. Purity is the percentage of a gas in the mixture. Gas purity refers to the proportion of gas present in a sample (Nigen, 2021). For example, the usage may require 99% nitrogen, or 99% oxygen. Specifications like USP dictate acceptable amounts of other gases present. Gas purity can be influenced or disrupted by leaks in the system, which can add ambient air to the mixture. It is also possible that the system could become incapable of producing an appropriate level of purity. Proper tubing (to reduce permeation), the appropriate regulator, and correctly fitted joints can help prevent other gases from affecting the process (Kandl, 2005). An inappropriate level of purity can have disastrous effects on the products or harmful effects on the consumer. 

Imagine trying to drink clean water through a dirty, contaminated straw. The purity of the water at the beginning will be diminished due to the distribution (the straw). The same is true for pure gases, which is why point of use testing for purity and contamination is critical. 

Pure gases are susceptible to contamination and a reduction of quality just like any other process air, compressed air, or instrument air. Contamination from particles, water, oil, microorganisms, or gases could be detrimental to the end product, resulting in recalls, illness, or a shortened system life span. Gaseous contamination refers to particles, water, oil, microorganisms and gases that may be impacting the gas. Most commonly, water, oxygen and hydrocarbons contaminate pure gases (Kandl and Bartram, 2015). Since they are abundant in the atmosphere, it is quite common for these contaminants to enter a pure gas system.

Contamination can also come from the distribution system itself. Ideally, all systems would be made of only stainless steel - the best material to use to avoid contamination. Piping like black iron or mixed metals produce large amounts of rust that often cause failing particle tests.  Additionally, metal shavings from maintenance or degradation of o-rings or hoses can all contaminate the pure gas. Condensation or humid ambient air from an intake or leak can add undesirable amounts of moisture to the gas which can cause microorganism growth. Depending on the type of system you have, further contamination can be introduced from nearby vehicles, cleaning supplies, or systemic oils themselves. Testing for particles, water, oil, microbes, and gases in these systems is an essential part of ensuring the quality of your pure gas. 


Point of Use Testing

Contamination can come from many locations and sources. In industries where quality and consistency are key, regular testing is the best way to monitor the purity of your gas over time. Pure gases used for critical end-products and that are administered to patients must be of appropriate quality.  Point of use testing reliably demonstrates these quality levels where it is most important. Since gases are regulated as “finished pharmaceuticals” by the FDA, they are expected to meet GMP requirements. The Joint Expert Committee on Food Additives (JECFA) sets purity limits for nitrogen gas used in food manufacturing, as does the FCC. CGA, EU 231, NFPA 99, and USP all also have requirements for pure gases. 

Facilities employ filtration to further ensure the quality of their pure gases. Filtration must be monitored, as an inadequate filter will allow contamination to pass through, leaving the end product or patient vulnerable to contamination. Testing before and after filter changes provides data to understand whether their filtration is working as expected. It is recommended to change all filters based on the OEM’s requirements, but some facilities have high levels of particulate matter which may require more frequent filtration changes. Point of use testing provides data on the efficacy of the filters and maintenance schedules. 

Point of use testing can be used as a comparison tool as well. Taking samples at the beginning of the distribution system, the middle of the system, and the point of use can help users understand if any part of the distribution piping is contributing to contamination. This could point to any issues with leaks, particulates, or residue. Knowing purity at the beginning of the line is helpful for troubleshooting, but at the bare minimum, manufacturers and suppliers must demonstrate that the gas at the point of use meets the users’ requirement. 

The best way to know that the distribution system and pure gases are maintaining quality levels as expected and that maintenance schedules are appropriate is to employ quarterly point of use testing to aid in trend analysis. However, for many standards and certifications, annual testing alone will meet the minimum requirements. 


How to Test

One challenge that users sometimes face is how to complete a pure gas test cost-effectively and efficiently. At Trace Analytics, we provide AirCheck Kits designed to quickly take pure gas samples at the point of use, or other points in your line. The AirCheck kits can test for purity and contaminants based on your needs and specifications. Made mostly of stainless steel parts, the AirCheck kits take pure gas samples quickly and easily. The sampling media (usually a filter, source bottle, and detector tube) are then shipped back to the laboratory for analysis. For microbial sampling, agar plates and an impaction sampler are shipped to the facility for testing and immediately returned for incubation and analysis. Calibration and validation documentation are available for some kits. Pure gas testing can help users meet standards like JECFA, FCC, CGA, EU 231, NFPA 99, USP, ISO 8573 and more.

Whether you’re testing nitrogen, oxygen, argon, or mixed gases, Trace Analytics has the expertise and experience to make the whole process simple and straightforward. Connect the AirCheck Kit up to your sampling point, take a short sample following our detailed instructions and receive results within 5 business days of receipt of the sample at the laboratory. Analyses are performed using GC-MS, optical light microscopy, laser particle counters, gravimetry, detector tubes, or Gram staining and phenotypic ID. Most specifications and certifications require a non-biased, third-party, accredited laboratory to perform analyses and provide results. Though in-house and in-line testing can be helpful at times, the best way to ensure your system is meeting requirements and your results are accurate and adequate is to use an accredited laboratory. With so much on the line, testing with a reputable and accredited laboratory can give users peace of mind. 



Regular testing of pure gases helps to ensure the safety of consumers and of end products. Whether the pure gas is used directly for medical patients, or in the manufacturing of food, beverages, or pharmaceutical products, quality is of the highest importance. Inadequate levels of purity or unsafe contamination can be detrimental to the products or consumers. Trace Analytics helps make point of use pure gas testing easy for users in all industries. For more information on pure gas testing, please contact our team of experts. 


About Trace Analytics

Trace Analytics, LLC, is an ISO 17025-accredited laboratory specializing in the analysis of compressed air. Testing at Trace includes the analysis of particles, water, oil, and microbial contamination according to ISO 8573 standards through the use of gravimetry, GCMS, microscopy, and Laser Particle Counter (LPC) techniques. To learn more, visit


About the Author

Jenny Irvin is the Business Development Director at Trace Analytics. With a background in marketing and sales, Jenny works diligently with her teams to provide the educational materials and exceptional service that Trace Analytics is known for. Contact Jenny at tel: 512-263-0000 Ext. 5, email:



Inmatec. (2021). Oxygen for the food industry. Inmatec.,the%20growth%20of%20anaerobic%20microorganisms.

Kandl, F. (2005, September 23). Ten Steps to Maintaining Gas Stream Purity. American Laboratory.

Kandl, F., & Bartram, R. (2015). Maintaining Gas Stream Purity. CleanPeaks.

Marco, J. D. (2020, July 30). 5 Common Medical Gases Used in Hospitals. CHT Healthcare.,Nitrogen%20(Medical%20Liquid%20Nitrogen),mixture%20for%20lung%20function%20tests.  

NiGen. (2021, January 31). Nitrogen Gas Purity Grades for Different Industry Uses. NiGen.

Rocky Mountain Air Solutions. (2018, January 11). How Atmospheric Gases Are Used in the Food and Beverage Industries. RMA.


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