Medical Device Link.

PACKAGE TESTING

Offered as lower cost option for emersion testing, SureTorque’s SureVac package integrity tester features a silent Venturi vacuum generator, and PLC.

At ASTM’s October 2006 meeting, ASTM subcommittees approved changes to standards covering tests for distribution simulation and package accelerated aging, and balloted physical testing methods for measuring the integrity of porous packages and materials.

“To date, there is no commercially available low-cost test for measuring porous package integrity. Manufacturers have come out with $100,000 machines that [most] companies can’t afford. Bubble tests are the best we have, but they are nonquantitative and cumbersome,” says Jim Zynda, sales manager, Test-A-Pack, Carleton Technologies (Orchard Park, NY).

Testing device manufacturers are developing a range of alternative methods for consideration as potential new ASTM standards in areas including water-vapor transmission through flexible materials and nonporous package leak testing. More-precise technology is needed for testing higher-barrier films and advanced constructions employing laminates and metallized film coatings that have emerged in recent years, says Tim Ascheman, engineering manager, Mocon (Minneapolis).

“We are finding that manufacturers are making better materials that are running into a sensitivity wall with our standard instruments,” Ascheman says.

Mocon has developed a coulometric sensor-based system that is more sensitive than infrared sensor technology in water-vapor-transmission measurement. “We want to develop a new standard for MVTR testing based on this technology,” says Ascheman.

Test-A-Pack plans to launch this year a nondestructive alternative method for burst, creep, and pressure-decay testing of nonporous packaging. The system employs a vacuum and pressure transducer technology, eliminating the need for destructive needles and sticky ports, says Zynda.

ASTM F2097 (Standard Guide for Design and Evaluation of Primary Packaging for Medical Products) is being updated to incorporate recent standards, including F2559-06 (Standard Guide for Writing a Specification for Sterilizable Peel Pouches), says Dhuanne Dodrill, chairman of ASTM Subcommittee F02.50. (A news story on F2559-06 will be in the February 2007 issue.)

DuPont has developed an apparatus for microbial barrier testing of porous packing using 1-µm polystyrene spheres instead of live microbes.

“F2097 is a fantastic reference tool providing a compendium of all the standards that are likely to be used when evaluating packaging for medical devices,” she says. New standards being incorporated into F2097 include the F2391-05 test method for measuring package and seal integrity using helium tracer gas, F2475-05 for determining appropriate package material biocompatibility testing, and F2476-05 for determining carbon dioxide–gas transmission rate through barrier materials, Dodrill says.

F2559-06 references ASTM methods for tensile and burst seal-strength testing.

For tensile testing following F88, the guide notes that because test results vary with the sample tail-holding method used, “consistent use of one technique should be negotiated with the supplier and indicated in the specification.”

To support consistent use in tensile-fixturing methods, new language has been added to F88 to designate the three fixturing methods as “A, B, and C” and with descriptive language on each, says Pat Nolan, COO of DDL (Eden Prairie, MN).

“When customers don’t spell out the testing method, we will go to the default test of a 90° unsupported tail, but then find out the customer wanted another technique. Tests can now be more clearly designated,” he says.

ASTM standard F99, which describes the standard practice for preparing a flexible-barrier-material specification, is undergoing a major rewrite in subcommittee F02.50, says Dodrill, subcommittee chairman and technical contact for F99.

“F99 has not been updated since 1976. There is a wide range of materials used in the industry and no real comfort level about creating a material specification using F99. The standard as it exists is not being used. We decided it would be more valuable to the industry if we created guidance similar to what has been written for preformed barrier pouches. The body of the text will be completely reworked, describing what should be considered when developing specifications for materials with different physical properties,” Dodrill says.

“We will go to a subcommittee ballot in April and, if all goes well, to main committee ballot in October,” she adds.

MEASURING POROUS MATERIALS AND PACKAGES

Addressing porous-package integrity testing, ASTM subcommittee F02.40 is in the process of approving a change to standard F2095. The change would allow the use of “film-forming coatings” to eliminate the porosity of porous packaging in pressure-decay leak testing. Donbar Industries Inc. (Long Valley, NJ) has developed an application for testing using its WholeSeal product.

“The new language was approved in October and will go out for full committee balloting,” says Donald Barcan, president, Donbar Industries. Barcan is also a member of PMP News’ editorial advisory board.

WholeSeal is an aqueous polyurethane emulsion that can be applied to porous surfaces to create a nonporous package for destructive seal integrity and package integrity testing.

The application supports porous package testing using a pressure-decay leak test that allows the quantification of leak rates, an advantage over commonly used porous package qualitative test methods such as underwater bubble and dye tests. WholeSeal detects smaller defects than those methods, to less than 50 µm in size, says Barcan.

“There are other methods for detecting leaks in porous medical packaging, such as those that use vacuum decay and CO2 tracer gas technologies, but those require expensive test equipment,” says Barcan.

Pressure-decay testing using the film-forming coating demonstrates leaks on the film side of the package as well as seal defects. “The seal area isn’t covered because WholeSeal doesn’t penetrate through the material, so you can discover defects such as channels in the seal area,” he says.

Barcan worked with T.M. Electronics (Boylston, MA) in bench testing the application. Barcan and Stephen Franks, executive vice president, T.M. Electronics, are drafting language to include the application in ASTM F1140 and F2054, which both cover package burst and creep seal-strength testing.

“Pressurizing the package relates to the package size and the amount of porous material. As packages get larger, air leaves the Tyvek walls faster than the test equipment can replenish it, and you can’t reach an adequate pressure to burst the package. WholeSeal zeros the porosity, allowing the tester to burst the package without high airflow,” says Barcan.

A nonmicrobiological method for microbial-barrier testing of porous packaging is heading to ASTM Committee F02 for a full-committee ballot, says Hal Miller, chairman of Committee F02. Miller is president of the packaging consulting firm PACE Solutions LLC (Cape May, NJ) and a PMP News editorial advisory board member.

“Nonmicrobial barrier testing using particle counters would give you real-time evaluation of materials. You can discover results in minutes, and the data correlate with data generated by the existing bacterial challenge test [F1608],” says Miller.

“In testing with live microbes, you have to wait seven days or more to incubate bacteria on an agar plate. A paper manufacturer can produce tons of paper in seven days before knowing lot test results,” he adds.

“There have been some limited repeatability studies, but no reproducibility studies. We are going to ballot with what we have [in order] to see what the committee feels about it,” says Miller.

PHYSICAL MICROBE BARRIER TESTING

DuPont Medical Packaging (Wilmington, DE) is working on behalf of the Barrier Test Consortium (BTC) to develop a test-fixture apparatus and method for measuring materials’ bacterial [resistance] using nonbacterial particles instead of live bacteria and cultures. BTC, formed by the Sterile Barrier Association, funded research by Air Dispersions Ltd. (Manchester, UK) that demonstrated that filtration characteristics of porous packaging materials are the same when challenged by actual bacteria or nonbacterial particles of the same nominal size.

DuPont has taken the initial work and developed the test method. F02 will ballot an updated version of the draft method. This updated version was previously approved at subcommittee level to address subcommittee balloting comments and to include data supporting the repeatability statement, says Paul Herman, technical support for DuPont’s Tyvek medical packaging business.

Since DuPont has the only available device for accomplishing the testing, reproducibility studies—those in which the same materials are tested in different labs using different devices—are not yet possible, Herman says.

“Typically, ASTM would like to have a precision-and-bias statement that incorporates repeatability and reproducibility data when a method is submitted. In this case, we are hopeful we can get it through committee with just the repeatability data, along with a statement that reproducibility data will be generated before the next review of the method in five years,” says Herman.

“We have done internal round-robin testing with different operators to demonstrate repeatability and will finish up the reproducibility data when someone else builds another unit,” he says.

Herman believes that no other units will be constructed until the method is approved.

The test method—“Using Aerosol Filtration for Measuring the Performance of Porous Packaging Materials as a Surrogate Microbial Barrier Test Method”—would be an alterative to F1608, which requires microbe culturing and the enumeration of colony-forming units.

DuPont’s apparatus includes a sample holder and aerosol generator for challenging material using 1-µm-sized polystyrene spheres. A laser-light particle-counting system produces real-time results that can go right into a spreadsheet to simplify data reduction.

“F1608 challenges the sample at a flow rate of 2.8 L/min. That is far greater than you would see in normal package handling. The dominant filtration mechanism is inertial impaction. When the airstream abruptly changes direction to get around a filter fiber, particles can’t change direction as fast, and their inertia causes them to slam into the fiber,” Herman says.

“We test at flow rates closer to real-life conditions. We can vary the flow rate, plot penetration versus flow, and generate a curve that tells you a lot more about the specimen,” he adds.

Two particle counters measuring aerosol-challenge particles and particles that penetrate the sample can be used for faster results.

The company has disseminated information on the system’s configuration, including diagrams and sample-holder-design drawings to BTC members.

PACKAGE TEST ALTERNATIVES

T.M. Electronics manufactures equipment for seal-strength and package-integrity testing of sterile-barrier flexible packaging. Its BT-1000 unit performs both pressure-decay leak tests for package integrity and seal-strength testing following ASTM F1140, F2054, and F2095.

“There is no one perfect method for package-integrity and seal-strength testing. Each solution adds to the practical capability for the user to find a method that best suits particular needs. In developing test equipment solutions, we will often manipulate fundamental designs to meet the varying requirements in the industry,” says Franks.

MDC Engineering Inc. (Sarasota, FL) has commercialized the SureVac package-integrity tester for bubble-emission leak testing and altitude simulation. SureVac features a self-contained and silent Venturi vacuum generator in lieu of a vacuum pump, says Jon Ford, sales manager. “We developed this test equipment initially to validate our Sure Pack form-fill-seal machine, when we found it was hard to find test equipment that we could calibrate to NIST standards in order to have current certification,” says Ford. “The SureVac emersion test unit is competitively priced for under $6000, with a PLC for running preset programs or cycling tests,” he says.

Mocon has debuted an apparatus that measures three package variables in one analysis. The Pac Check Model 820 and Model 840 package integrity analyzers determine leak hole size, measure package volume, and examine oxygen headspace, with software that stores up to 240 individual product test methods. The analyzer works by creating a vacuum instead of employing positive pressure to inflate the package. “We are pulling a vacuum on the package and measuring void volume. When you pull a package in on itself, the package becomes rigid. The measurement is more sensitive because you can put a bigger differential pressure across the package without bursting it,” says Mocon’s Ascheman.

Mocon’s InFlux vacuum/flow method measures absolute aggregate hole size following Poiseuille’s law. Pressure and flow are measured, after the operator keys in material thickness and seam widths.

“The big benefit over positive pressure fall-back tests is that vacuum/flow method results are not influenced by the size of the bag. Pressure-decay testing will produce different values for large and small bags in a fixed-time period. A small bag will lose a larger percentage of its total volume. Using positive pressure, you can only compare decay rates for the same sized bags and for the same material types,” he says.

“We would like to make the influx vacuum/flow method an alternative method to pressure-decay testing. We also intend to work on development of a standard for the use of headspace analyzers, which are presently not addressed by ASTM,” Ascheman adds.

CAPS, BOTTLE SEALS, AND BLISTERS

MDC Engineering Inc. acquired SureTorque this year. At Pack Expo International 2006, the companies debuted SureTorque’s STM 120M motorized torque tester, which uses a servomotor for precise control over cap torque and turning speed. A floating-head design suspends the bottles to minimize top-load pressure during continuous-thread (CT) cap release and tamper-evident band-break testing.

The unit tests a wide variety of closure systems such as push-and-turn and continuously threaded designs as well as induction seals. “Our pharmaceutical customers wanted 360° rotation and control over the cap to know how far the cap turns before it is released,” says Ford.

SureTorque has recently developed special fixturing for torque testing of luer tips on syringes and catheters. “A lot of this is R&D work. We have three in-house jobs going now. We just installed two torque testers that are being used like a capping machine, providing accurate torque for capping catheters,” he says.

While motorized torque testers may be used for more-controlled and more-accurate lab testing, manual testers provide a cost-effective solution for production testing, says Mark Fridman, marketing manager, Mark-10 (Copiague, NY).

“Our manual testers are used for laboratory and assembly line testing. A motorized unit provides more-accurate testing and consistency between tests by loosening the cap at a controlled rate. In a manual system, values will vary depending on how quickly the cap is being turned. But manual testers are more cost-effective and portable,” Fridman says.

In manual testers, Mark-10 offers the Series CT Cap Torque testers for capturing peak torque in both turning directions. The CT units feature a solid aluminum housing, optional jaws as an alternative gripping method, and optional WinWedge software for transferring data to a Windows PC.

T.M. Electronics offers equipment that employs customized test chambers for performing pressure-decay or vacuum-decay leak testing of blisters and bottle induction seals.

The T.M. Solution-C blister card test system provides a nondestructive test for leaks in blister card seals and material. Air pressure or vacuum is supplied to a test chamber enclosing the blister, and chamber air space is tested for pressure decay, detecting pinholes and defects as small as 5 µm. The same fixture can be configured to handle a variety of blister card sizes and shapes using interchangeable inserts.

Another sealed-fixture system provides an alternative to water immersion for testing induction-welded bottle seals.