Dye penetration testing is a common method of checking for seal leaks in medical packaging such as pouches, trays, and blisters. The intent of this article is to review and clarify the recent developments in test methods for both Porous (ASTM F1929-12) and Nonporous (ASTM F3039-13) packaging.
ASTM F1929 – 12 Standard Test Method for Detecting Seal Leaks in Porous Medical Packaging by Dye Penetration.
ASTM F1929 defines materials and procedures that will detect and locate a leak equal to or greater than a channel formed by a 50 μm (0.002 in.) wire in package edge seals formed between a transparent material and a porous sheet material. A dye penetrant solution is applied locally to the seal edge to be tested for leaks. After contact with the dye penetrant for a specified time, the package is visually inspected for dye penetration.
The only test method prior to the 2012 revision was Injection of the dye solution inside the package (Method A). With the 2012 revision two new test methods called the Edge Dip (Method B) and Eyedropper (Method C) were introduced. These provide the user flexibility of three proven and standardized methods to choose from when performing package seal integrity testing.
- Method A – Injection: The method involves injecting dye into the package along the longest seal edge with a depth of approximately 0.25 inches or 5 mm of dye. The dye is allowed to contact the sealed edge for up to five seconds. A channel in the seal would be detected within this time, if present. The package is then rotated in order to expose the dye to the remaining sides of the package. Total visual inspection time should be less than 20 seconds for a four sided package.
- Method B – Edge Dip: This method involves dipping the side of the porous pouch, bag, or tray into the dye solution and allowing for capillary action to pull the dye up, detecting a channel in the seal. This method may be preferred because it is faster, safer (does not require a syringe for injection), less messy (does not expose the device to dye), and uses less dye solution.
- Method C – Eyedropper: This method uses an eye dropper or pipette to apply the dye solution to the outer edge of the package seal. This method is especially useful for lidded trays with a stepdown flange or when the seal is set back from the edge. Chevron seals also work well with this method when the pouch is not trimmed for an Edge Dip test.
False Positive Guidance
Guidance on false positive observations using the dye solution is another major revision to the standard. The appendix addresses wicking, oxidative sterilization (gas plasma), and bending/folding of materials that have caused confusion and misinterpretation of this method. Users will find interpretation of these issues to be easier to understand.
ASTM F3039-13 Standard Test Method for Detecting Leaks in Nonporous Packaging or Flexible Barrier Materials by Dye Penetration
This test method is used for both transparent and opaque nonporous surfaces and it will detect and locate a leak equal to or greater than a channel formed by a 50-µm [0.002-in.] wire in the edge seals of a nonporous package. The procedure is similar to ASTM F1929-12, Method A with two exceptions:
- The dye solution uses a 3% surfactant as opposed to a 0.5% in the porous package method.
- The inspection involves use of an absorbent material, which will provide evidence of dye staining.
Inject the dye penetrant into the package or along sealedge at a volume of at least 0.25 ml per 25 mm [1 in.] of seallength. Allow the dye penetrant solution to remain in contact with the seal edge for approximately 5 s. Channels will be detected within this time period.
- If the package has a transparent side (e.g. film), the seal may be examined visually through this side.
- If the package is opaque (e.g. foil) or if additional verification is desired, the outside edge of the seal being tested should be placed against an absorbent surface for approximately 5 s. After carefully lifting the package the presence of stains indicates a channel or leak.
- Rotate the package as necessary to expose each seal edge to the dye penetrant solution and repeat the examination.
LSO has performed medical package integrity tests per applicable ASTM standards for two decades. While it is assuring to finally have a guideline in place for testing of non-porous packaging, our experience over the years shows that for porous packaging, method A has been consistent across a variety of package designs and therefore, is our preferred dye penetration test procedure. Regardless, we will actively work with you to choose the best option for integrity testing of your specific medical device package.