Oxygen transmission rate (OTR) testing measures the steady-state flow of oxygen through a finished packaging container under controlled conditions of temperature and humidity, providing the essential data needed for material selection, shelf-life modeling, and quality control. This technical guide explains the test principle, applicable ASTM, ISO, GB, and JIS standards, typical sample types, step-by-step procedures, and frequently asked questions for manufacturers of food, beverage, pharmaceutical, and cosmetic packaging.
Oxygen transmission rate (OTR) testing quantifies how much oxygen permeates through a sealed packaging container over time, delivering objective barrier-performance data for packaging design, supplier qualification, and regulatory submission. Below is a structured overview of the principles, standards, samples, methods, and applications of whole-container OTR testing.
Technical Overview
Oxygen transmission rate, also referred to as oxygen gas transmission rate (OGTR), is the steady-state rate at which oxygen molecules diffuse through a package wall, closure, or seal under specified temperature and relative humidity conditions. For finished containers, OTR is typically expressed in cubic centimeters of oxygen per package per day, cm³/(package·day), whereas flat packaging materials are reported per unit area, cm³/(m²·day). Because oxygen ingress drives lipid oxidation, vitamin degradation, aroma loss, discoloration, and aerobic microbial growth, OTR is one of the most decisive parameters in packaging design and shelf-life validation.
Material-level testing of flat films cannot fully represent a finished container: heat seals, side seams, thermoformed corners, material thinning, and closure systems frequently dominate real-world oxygen ingress. Whole-container testing therefore measures the package as a complete system, including every potential transmission path. This distinction is critical for high-barrier products, where the closure or seal may contribute more oxygen than the barrier wall itself.
OTR is strongly dependent on environmental conditions. Permeation follows an Arrhenius-type relationship with temperature, so OTR increases sharply as temperature rises. Humidity also plays a major role: hydrophilic barrier polymers such as EVOH and nylon lose a significant portion of their barrier performance at high relative humidity. Consequently, all OTR results must be reported together with the exact test temperature and relative humidity.
- ASTM F1307 – Standard Test Method for Oxygen Transmission Rate Through Dry Packages Using a Coulometric Sensor
- ASTM D3985 – Oxygen gas transmission rate through plastic film and sheeting using a coulometric sensor
- ASTM F1927 – Determination of OTR at controlled relative humidity through barrier materials using a coulometric detector
- ISO 15105-2 – Plastics, film and sheeting, determination of gas-transmission rate by the equal-pressure method
- GB/T 19789 – Determination of oxygen gas transmission rate of plastic films and sheeting, coulometric sensor method
- JIS K 7126-2 – Plastics, determination of gas transmittance, equal-pressure method
Testing Samples
Rigid Plastic Containers
Bottles, jars, jugs, and jerricans produced from PET, HDPE, PP, and multilayer barrier structures containing EVOH, nylon, or inorganic barrier coatings are tested as complete units with their production closures applied at the specified torque. Thermoformed cups and trays sealed with lidding films are tested in their finished, sealed configuration.
Flexible Packages
Stand-up pouches, pillow bags, sachets, coffee bags fitted with one-way degassing valves, and retort pouches are sealed using the customer's converting parameters and submitted in their retail-ready configuration. Both monolayer and high-barrier foil or metallized laminates can be evaluated.
Closures and Complete Packaging Systems
Caps, liners, induction seals, and dispensing closures can be tested individually on standardized fixtures or tested assembled with the container to isolate their contribution to total oxygen ingress. This is essential for verifying whether a barrier upgrade is needed on the wall or on the closure system.
Pharmaceutical and Nutraceutical Containers
Tablet bottles, dropper bottles, glass and plastic vials, and blister configurations are tested empty to characterize the inherent barrier of the packaging system, supporting stability studies and container-closure qualification programs.
Testing Items
Typical test programs offered by accredited third-party laboratories and in-house packaging laboratories include the following items:
- Whole-package oxygen transmission rate at 23°C under dry conditions
- OTR at controlled elevated relative humidity (for example, 50% RH, 85% RH, or 90% RH)
- Accelerated OTR testing at elevated temperatures such as 38°C or 40°C for rapid screening and shelf-life extrapolation
- Cumulative oxygen ingress projection over the intended shelf life, combining OTR data with headspace volume
- Comparative evaluation of competing structures, coatings, and closure designs
- Lot-to-lot quality-control release testing for barrier materials and converted packages
Testing Methods
Coulometric Sensor Method (ASTM F1307)
The coulometric method is the internationally recognized referee technique for whole-package OTR. The container is mounted on a dedicated fixture in a test chamber. Its interior is continuously swept by a stream of high-purity nitrogen carrier gas containing a small percentage of hydrogen, while the exterior is exposed either to ambient air or to a pure oxygen stream. Oxygen that permeates through the package wall is entrained by the carrier gas and delivered to a coulometric fuel-cell sensor, which generates an electrical signal directly proportional to the mass flow of oxygen. Testing continues until the signal reaches steady state, after which the OTR is calculated and reported.
- Step 1: Condition the samples at a standard atmosphere (typically 23°C, 50% RH) before testing.
- Step 2: Mount the container on the test fixture, sealing any required openings with barrier plates and epoxy or mechanical seals.
- Step 3: Verify package integrity with an appropriate leak check to eliminate false results from gross leaks.
- Step 4: Purge the package interior with nitrogen carrier gas until residual oxygen is fully removed.
- Step 5: Expose the exterior to ambient air or a controlled oxygen stream and begin monitoring.
- Step 6: Record the sensor output until a stable steady-state transmission value is achieved.
- Step 7: Calculate OTR in cm³/(package·day), applying an air-to-oxygen correction factor if ambient air is used as the source.
Test Conditions and Reporting
Unless otherwise specified, testing is performed at 23°C ± 2°C under dry conditions in accordance with ASTM F1307. Accelerated and humidity-controlled conditions can be selected to simulate tropical climates, hot-fill storage, or retort processing histories. The final report should state the test standard, temperature, relative humidity, oxygen source, steady-state evidence, individual and mean OTR values, and full sample identification including closure torque and sealing parameters.
Film-Level Screening Methods
Before package conversion, flat materials can be screened using ASTM D3985 or ISO 15105-2 in a two-chamber permeation cell, in which one side of the film is swept with carrier gas and the other is exposed to oxygen. ASTM F1927 extends this approach with independent relative-humidity control on both sides of the specimen, which is essential for humidity-sensitive barriers such as EVOH. GB/T 19789 and JIS K 7126-2 define equivalent national procedures.
Alternative Techniques
Dynamic accumulation methods coupled with fluorescence-based oxygen sensors, as well as carrier-gas infrared detection, are available for rapid screening and for monitoring total oxygen ingress inside filled packages, including headspace oxygen. These techniques complement, but do not replace, the coulometric package method when a referee result is required.
Applications
OTR data underpin packaging decisions across every sector where product quality depends on limiting oxygen exposure. Typical use cases include:
- Beverage packaging: barrier PET bottles for beer, wine, juice, tea, and dairy drinks, where total oxygen ingress targets are often below 1 ppm over the shelf life
- Food packaging: nuts, snacks, roasted coffee, dried fruits, edible oils, sauces, and modified-atmosphere trays and lidding film combinations
- Pharmaceutical and nutraceutical packaging: oxygen-sensitive tablets, effervescent formulations, softgels, and container-closure qualification for stability programs
- Cosmetics and personal care: formulations containing oxidizable oils, vitamin C, or other reactive actives
- Industrial and electronics packaging: oxygen-sensitive chemicals, adhesives, and specialty components requiring controlled storage atmospheres
Combined with headspace volume and product oxygen-consumption kinetics, OTR results feed directly into shelf-life models that predict the end of the period during which the product remains within specification.
FAQ
What does OTR mean and what units are used?
OTR is the steady-state rate of oxygen permeation. Whole containers are reported in cm³/(package·day), while flat films are reported in cm³/(m²·day); older North American data may appear in cc/(100 in²·day).
Why test the finished container instead of only the film?
Seams, seals, thermoformed corners, wall thinning, and closures often contribute more oxygen ingress than the flat material itself. Whole-package testing captures the total system performance and is the basis for realistic shelf-life claims.
How long does a whole-package OTR test take?
Standard packages may reach steady state within hours, while high-barrier multilayer containers can require several days to a few weeks because permeation must fully equilibrate before a valid result is recorded.
How do temperature and humidity affect OTR results?
Raising the temperature significantly increases the oxygen permeation rate, and high humidity can reduce the barrier performance of polar polymers such as EVOH and nylon by an order of magnitude. Testing should therefore reflect, or be corrected to, actual storage conditions.
How are leaks distinguished from true permeation?
Laboratories perform pre-test leak checks, use validated sealing fixtures, and may compare results with and without the closure or run replicate specimens. A sudden non-steady signal or abnormally high result typically indicates a leak that must be resolved before reporting.
What sample preparation is required?
Samples should be representative of production, conditioned at a standard atmosphere, sealed and closed exactly as intended for commercial use, and submitted in sufficient quantity, typically a minimum of three specimens per condition.
What OTR values indicate a high-barrier package?
Indicatively, aluminum foil laminates measure below 0.005 cm³/(m²·day), coated and EVOH-based multilayer structures fall roughly between 0.05 and 1 cm³/(m²·day), and monolayer PET film measures around 100 cm³/(m²·day). Acceptance limits, however, are always product-specific and should be derived from shelf-life requirements.