Bubble Emission vs. Dye Penetration Package Leak Testing
What is bubble emission testing?
Bubble emission testing is a pass/fail package integrity test that examines packaging systems containing gas headspace for leaks. ASTM 1929-15 governs bubble emission testing methods.
What is dye penetration testing?
Dye penetration testing is a qualitative pass/fail package integrity test that uses dye to detect leaks in porous and nonporous packages. ASTM D3078-02 governs porous packaging testing, and ASTM 3039-15 covers nonporous package testing using dye penetration methods.
Why are bubble emission and dye penetration testing important?
Medical devices and products can be contaminated through packaging leaks. These leaks are often found at small pinholes in the packaging or breaks in the seals between packaging components that allow the escape or entrance of substances or microorganisms into a sterile barrier system. Defects in seal channels can be detected via dye penetration testing. Dye penetration procedures are good for detecting individual package leaks without vacuum. Bubble emission testing is excellent at identifying large leaks in flexible packaging under a vacuum. Both bubble emission and dye penetration testing detect leaks that could cause contamination to medical products and risk patient health upon use.
What types of packages can be tested with bubble emission testing vs. dye penetration testing?
Bubble emission testing is performed for flexible packaging systems. The dye penetration testing methods for ASTM D3078-02 are limited to porous packaging materials with a transparent material on at least one side of the package. In contrast, the dye penetration testing methods of ASTM 3039-15 are used for both transparent and opaque nonporous materials that have appropriate contrast with the dye penetrant used for testing. You can test fully packaged medical devices, empty packages, or seal edge samples for dye penetration. Commercial fully packaged and terminally sterilized medical devices are evaluated using dye penetration testing to ensure packaging systems meet FDA package integrity requirements. Bubble emission testing can be performed with empty packages or packaged products.
How is bubble emission testing performed?
An immersion fluid such as water, water with a wetting agent, denatured alcohol, or mineral oil is used for bubble emission testing. Then the sealed package is placed within a vacuum chamber and fully submerged in the immersion fluid. The surface of the specimen needs to be completely covered with at least an inch of fluid for submersion. Next, the cover on the vacuum chamber is set, and the vacuum is turned on. The vacuum level chosen is as large as possible to create maximum sensitivity for the test. The vacuum level will vary based on the specific needs of the packaging system being tested. The degree of package expansion and test-fluid vapor pressure influence the maximum vacuum pressure that can be held. As vacuum pressure rises, the submerged package is assessed for air bubbles that indicate a leak in the packaging system. The vacuum is held for around 30 seconds, during which time the submerged specimen is again examined for leaks via air bubble emissions. The vacuum is then released, and the package is examined for any test fluid leaks inside the sterile barrier system. Multiple packages may be tested simultaneously if every package can be adequately observed for leakage during the procedure.
If bubbles indicating a leak are present under full vacuum or the rise of vacuum, the package failed the bubble emission test. If fluid resides inside of the packaging system after the test, the packaging also fails the test. If no bubbles due to leakage are observed, and no fluid due to leakage exists inside the package following testing, the packaging system passes the test. If a flexible package has little or no headspace, leaks cannot be reliably assessed with bubble emission testing.
How is dye penetration testing for porous materials performed?
Injection, edge dip, and eyedropper techniques are used for dye penetration testing of porous materials. In all three dye application methods, Toluidine blue is recommended as the dye indicator for the dye penetrant solution.
Injection Method
The first and most common method for dye penetration testing is the injection method. In this method, the dye penetrant solution is injected via a hypodermic needle. Flexible tubing is attached to the syringe instead of a needle to prevent accidental puncturing of the packaging material during testing. For the injection method, dye solution is injected to cover the longest package edge to a depth of 1/4 inch. Following administration of the dye, the seal area is visually examined through the transparent side of the package. Any channels in the seals will be readily detected within five seconds. This process is then repeated for the remaining sides of the package.
For all dye penetration testing, evaluation of the dye must occur within five seconds of application maximum. The visual examination must be performed within five seconds of dye application, as prolonged exposure of the dye solution on the packaging can result in dye wicking through the porous packaging material. When evaluating package seals, technicians look for penetration of the dye solution across the seal. If penetration occurs, this indicates that there is a leakage in the package.
Edge Dip Method
The second method for dye penetration testing is the edge dip method. For the edge method, a container with a length long enough to accommodate the longest edge of the package seal is selected. A dye solution is then poured up to 1/4 inch in height within this container. If the package tested has excessive material beyond the seal (such as a Chevron style opening), a modification excess material will be removed from the package. Excess material will be cut such that only 1/8 inch of material is remaining from the seal. Once extra material has been removed, an edge of the package under evaluation will be dipped just long enough to wet the entire packaging edge thoroughly. Any seal channels are detected within five seconds. This process is repeated for the remaining sides of the package.
Eyedropper Method
The third and final method for dye penetration testing is the eyedropper method. For the eyedropper method, a package needs to have an unsealed area beyond the outer edge of the seal. Once the unsealed area is confirmed, the eyedropper method can begin. First, a dye solution is poured into an open container. Next, a finger or the end of a paperclip is used to brush back the long edge of the porous material away from the transparent edge. An eyedropper or pipette is then inserted into the dye solution. With the transparent side of the package facing the technician, a bead of dye solution is placed along the top edge of the package between the transparent and porous material. The entire package border is wetted with this dye solution, and the seal is evaluated within five seconds for any leaks. This method is repeated for all sides of the package.
How is dye penetration testing for nonporous materials performed?
There are two methods for dye penetration testing for nonporous materials. In Method A, channel leaks in the seal are evaluated by injecting dye penetrant into the package or along the seal edge. The dye penetrant solution will detect any channels in the seal within five seconds. Method B tests for holes or leaks in a flat surface using a saturated absorbent pad. For Method B, the test sample is placed on top of the absorbent pad. Then the surface of the test sample is wiped with dye penetrant solution. Next, a roller is applied to the top of the packaging test sample to ensure contact between the absorbent surface and the bottom surface of the packaging sample. Excess dye is wiped from the packaging sample, and the absorbent surface is examined for any stains. The presence of pigments indicates holes or leaks in the package.
Summary
Overall, bubble emission testing and dye penetration testing are pass or fail methods for detecting leaks in packaging. Bubble emissions testing is performed under vacuum and only has one method. Dye penetration testing has five methods. There are three methods of dye penetration testing for porous materials: injection, edge dip, and eyedropper methods. The other two methods for dye penetration testing, Method A and Method B, are reserved for nonporous materials and test for leak channels and leaks in flat surfaces, respectively. All in all, when outsourcing your package integrity testing, choose a contract manufacturer capable of meeting the needs of your unique medical device or product.
MycoScience is a contract manufacturing organization specializing in sterile syringe and vial filling. MycoScience also offers Preservative Efficacy Testing, Sterilization Validations, Bioburden Testing, Cleaning Validations, Microbial Aerosol Challenge Testing, Accelerated Aging, Microbiology Testing, Cytotoxicity Testing, Bacterial Endotoxin Testing, EO Residual Testing, Package Integrity Testing & Environmental Monitoring services medical devices and allied industries. MycoScience is an ISO 13485 certified facility.
References
American Society for Testing and Materials. Standard Test Method For Determination Of Leaks In Flexible Packaging By Bubble Emission. West Conshohocken, PA, United States. (ASTM D3078-02).
American Society for Testing and Materials. Standard Test Method for Detecting Seal Leaks in Porous Medical Packaging by Dye Penetration. West Conshohocken, PA, United States. (ASTM F1929-15).
American Society for Testing and Materials. Standard Test Method for Detecting Leaks in Nonporous Packaging or Flexible Barrier Materials by Dye Penetration. West Conshohocken, PA, United States. (ASTM F3039-15).
