Rubber stoppers serve an important purpose within the pharmaceutical industry – protecting active ingredients from the external environment. But, even though they create an airtight seal, the rubber itself can affect the ingredients it was designed to protect.
Keeping pharmaceutical ingredients within a controlled moisture content range is essential for long term storage and drug efficacy
Because rubber is inherently hygroscopic and prone to moisture absorption, it can affect the moisture levels of ingredients within a vial. To combat this, many pharmaceutical companies test their rubber stoppers as a part of their quality assurance monitoring process.
Moisture analysis of rubber stoppers has traditionally been performed using Karl Fischer (KF) titration
Although the results are both accurate and precise, the testing process itself can be lengthy and somewhat complicated. And with replacement glassware and chemical reagents a common enough purchase that one might consider an Amazon Dash button, upkeep of a Karl Fischer titrator is by no means inexpensive or necessarily easy. Special training is required to operate a KF with the consistency needed to obtain accurate and repeatable results, both of which are essential when it comes to medical devices. When the slightest defect can mean the difference between saleable product and a pile of scrap, you need an instrument you can depend on.
Computrac® offers a user friendly, chemical free alternative to Karl Fischer
The Computrac® Vapor Pro® series of instruments, which includes the new Vapor Pro® XL (VPXL) as of August 2016, utilizes a moisture specific relative humidity (RH) sensor to calculate the moisture content of a given sample faster and without the use of chemical reagents. They correlate well with Karl Fischer and zero specialized training is required. Regular maintenance is also significantly easier than Karl Fischer, which requires frequent cleaning and replacement of hazardous chemical reagents and expensive glassware. And because not all moisture testing is done in a lab environment, Computrac moisture analyzers have been engineered to deliver lab precision data whether they are in the lab or on the production floor.
The data presented below demonstrate five stopper samples of varying moisture content, size and composition
In order to analyze the moisture content of rubber stoppers using a KF coulometric titrator with an oven attachment, four stoppers were cut into eight pieces of relatively equal size. The cut pieces were then mixed and five pieces were randomly selected for testing. To perform moisture analysis with the Computrac® Vapor Pro®, a single, intact stopper was chosen and placed in a vial.
The Computrac® Vapor Pro® Series Correlates well with Karl Fischer
For all tests, the average result on the Vapor Pro was within the KF margin of error with the added benefit of shorter test times on average than Karl Fischer.
While the accuracy and precision of Karl Fischer titration when performed by a trained professional is well known and accepted, Computrac® has proven to be just as accurate and precise while being significantly easier to operate. Further, the Vapor Pro series yields quicker test times with smaller standard deviations when compared to the traditional KF method.
If you have any questions or would like to learn more, contact us online or give us a call at (800) 528-7411. If you aren’t ready to speak with someone quite yet, check out our application pages for more information about testing the moisture content of pharmaceuticals, foods, plastics and medical devices.