Isolation in Sealed Containment
If you can perform your process in a fully sealed test tube, flask or tank, then isolation is usually pretty easy. If you need to isolate the process from radiation, vibration or temperature variations, then additional work may be needed, but atmospheric isolation is not typically a problem in laboratory glassware or other sealed containers. The problem usually arises when sampling, measurement or other process action requires that the container be opened. If that is done in the air we breathe, then contamination may happen when oxygen, water vapor, CO2 or particulate are not OK.
Still, even when the process has multiple steps, sometimes it is possible to use workarounds to complete transfers. measurements or sampling without “popping the cork” and exposing the whole batch to an ocean of atmosphere. In most cases, if sealed containment is easy, it is being done, which is why use of laboratory glassware is so common. However, in many labs and shops, enough processes require opening the container that work in a hood is now routine. In many cases this is fine, but in others it is a breach of isolation integrity, and an invitation to contamination.
Keeping a Cork in it
A lot can be done to improve isolation by simple training, awareness and priority on keeping isolated specimens sealed in a container when possible. The following steps can enhance results by increasing the power of sealed containment if every time opening an isolation container we:
- Realize the high contamination risk of work in a fume hood (cupboard) due to the constant flow of room air past materials and processes performed there
- Ask if this step could be completed in the sealed container by some form of external manipulation, observation or non-invasive testing
- Consider the option of closed transfer systems such as use of syringe or tube-through-stopper transfers on the counter or in the hood
- Consider performing this process step in a pressurized, controlled isolated space like a glove bag, barrier isolation glove box or sealed plastic bag.
- See if open time in a hood can be minimized, exposure controlled and sealed containment restored with less risk of contamination or exposure by use of local purging, blanketing or other means
Knowing When the Cork Must Go
Of course, when the work MUST be completed in an open container or outside the container, it is critical that this be acknowledged so action can be taken to meet isolation requirements. In such cases it is important to make use of the isolation technology that best meets the needs of the process, while providing practical solutions, safety and results.
If you just pop the cork and do it quickly on the counter, you could pay a high price for poor risk management. However, massive overkill (huge, heavy glove box with vacuum pumps and a chemical dry train loop) could take far longer to deliver, install, set up and operate than your schedule allows, and it may come with risks to reliability, operating complexity and schedule that prove more costly than no isolation at all.
The best solution will be one that leverages advantages of in-sealed-container isolation while providing the open/out isolation that fits best, and is right sized for your process requirements.
4 thoughts on “Sealed”
Excellent post about isolation in sealed containment. I think you have listed a lot of good things to keep in mind to avoid unnecessary contamination.
Thanks for joining the discussion, Marika. The main point of this article is that while large, complex isolation equipment has its’ role, the simplest isolation solution is closing the stuff to be isolated in a test tube, jar or other sealed container. Usually smaller and simpler is better, if it is possible.
I totally understand the importance of sealing containment. In grad school, I used cylindrical acrylic containers filled with half water and half sediment to measure oxygen fluxes (respiration), and would have to open them with a rubber cork to measure dissolved oxygen every 2 hours over a 24-hour period. It was challenging to ensure that these were sealed properly, and you could see it in the data when the seal was not 100% effective.
Thanks, Ciara. That’s an excellent example of sealed isolation and dealing with a protocol for how and when to open and seal it. Too often the choice is made to resort to a complex enclosure isolation scheme when a simple protocol like your would work as well or better, with far less hassle.
Thanks for sharing your story.