Q: Is there an ASTM method for this instrument/technique?
A: Not at this time, but we're working on it. ASTM methods are concensus standards and MOCON can't be the sole driver of the method. Round robin testing is required with every ASTM standard method. With all of that said, the Aquatran follows a similar methodology for test configuration as ASTM F-1249, except that the Aquatrace sensor is coulometric and not infra-red.
Q: Can the Aquatran be daisy chained to other Permatran masters? Do you need updated software?
A: The Aquatran follows the same connectivity methods as MOCON's other instruments. An Aquatran needs to be attached to another Aquatran MG module and would not work with a Permatran-W 3/33 MG module or Oxtran ML module. However, with MOCON's Permnet software, up to ten different instruments and instrument types (i.e. oxygen, water vapor and carbon dioxide analyzers) can run together. Permnet also allows the ability to archive and retrieve data at a later date.
Q: What is the upper end of the test range? It would be nice to run good/bad samples or high/low temperatures on the same instrument.
A: The range of the Aquatran instrument is 0.0005 to 5 g/(m2 day). The temperature range is 10-40C for the G (100%RH and 35-90%RH )module and 5 to 50C for the W (100%RH only) module. The instrument has been verified across its test range.
Q: What is the temperature range of the Aquatran itself vs the remote cells in the oven?
A: Remote cells can test up to 85C with 100%RH. When temperatures get much higher, water loss through evaporating and pressure on the film can become an issue. We do vent the remote cells to avoid pressure problems.
Q: How do you know when the detector is exhausted?
A: The Aquatran sensor is coulometric. When it starts to loose it's efficiency (i.e. values drop), the sensor needs replacement. The instrument does not require calibration, but should be periodically checked for efficiency with a low level N.I.S.T. film.
Q: If this equipment does not require calibration (a primary method), then why does the availability of NIST calibration standards matter?
A: The N.I.S.T. films are used for verifying the sensor and also for some customers (such as pharmaceutical) provide a practical assurance that the instrument is operating correctly.
Q: Do you have experience evaluating the permeation of materials like Tyvek using the Aquatran?
A: No. Tyvek is considered a higher transmitter and would be better tested with a different instrument. Tyvek is so high of a water vapor transmitter that it's often used as a breathable building wrap and the pouch for desiccant packs.
Q: Is it possible to evaluate the WVTR of package like thermoformed PET tray with the Aquatran?
A: Yes, packages can be tested with the Aquatran. From our experience, unless coated or very small, the thermoformed PET tray could readily be tested with our Permatran-W 3/33 instrument as well.
Q: Could you explain how we can do the high temperature and high humidity like 80oC/80% RH?
A: Using the MOCON remote permeation cell, a film can be tested at 80C. However, our cell configuration is for 100%RH beneath the film. Our concerns for precise humidity testing at the high temperature are two fold. 1. Using a good oven with 100%RH as the test gas will guarantee better repeatability from lab to lab. 2. Having accurate RH probes in this environment requires calibrating them in the same high temperature environment, which proves difficult.
Q: What is your procedure for testing Blister cavities?
A: Blister cavities can be tested in two manners. 1. A cavity is sealed with water inside and placed within a capture vessel with nitrogen purging around the sample. Water vapor transmitting out of the samples is then analyzed by the Aquatran and quantified. 2. The "cavity only" is epoxied to an impermeable substrate (such as a brass plate) with nitrogen lines affixed to the plate to allow nitrogen to sweep within it. A controlled humidity is then placed around this mounted blister/plate sample. All water vapor that transmits through the blister is swept by the nitorn carrier gas stream to the Aquatran and quantified.
Q: Has the Aquatran been used to measure the WVTR of aluminum foil used in blister packaging of pharmaceuticals?
A: Yes. Actual foil is still an extremely good barrier and below the detection level of the instrument, providing it is faily "pristing". If wrinkled or poorly sealed, the overall blister packaging can be analyzed (described above) to gauge the overall package performance. This is important, because water can permeate through adhesive layers or sealing layers of a blister cavity. So comparing the "blister only" to a "sealed blister" test allows one to see how well the foil performs.
Q: Is it possible to use the same sample for multiple tests?
A: Yes. As with MOCON's other instrumentation, samples can be tested repeatedly. The N.I.S.T. films can be repeatedly tested throughout it's one-year life with no adverse effects. However, we do caution that "fragile" films (ones that are adversely affected from handling (i.e. such as glass coating that can "crack" or a substrate that can "swell") be mounted w/in more rigid foil masks to provide additional support, if moving between instruments.
Q: How often do you need to change P2O5?
A: Depends on what materials are being tested. MOCON warranties the sensor for 1 year. If a lot of high transmission rate samples are being analyzed, then the sensor won't last as long as one that is continually testing low-level films. In our lab, we've used Aquatran instruments for over three years without needing a new sensor. However, we're continually testing only the lowest level films. We test higher level films on our Permatran-W 3/33's.
Q: What's the difference between the Aquatran and the Permatran?
A: The key difference is with the sensor technology. The Aquatran is 10X better than the Permatran for low-level testing. Additionally, the Aquatran does not require calibration (only periodic verification of it's absolute sensor).
