Ya know, syringe filtering right into sterile sealed vial avoids all this. If your new to home brewing I wouldn't suggest going this route. To risky. I don't even like doing it but I've managed to master it.
The caulking gun and syringe filter is the best.
Friend, you or I am missing something. I think you are talking transferring the parenteral aseptically.
I was in no way even speaking of vials and stoppers.
I was talking in making the parenteral solution BEFORE filtering into sealed Sterile vials. It is pure board misinformation that .2 micron filters and BA solve all issues. BA will kill bacteria sure, but, what happens at death of gram negative bacteria? They release Endo toxins to poison/kill whatever killed them. It's a species survival mechanism. If it is gram positiveive bacteria it releases exotoxins which can be far more troublesome.
Both ends and exo will filter through .2 and BA will not deactivate them.
Endo toxins will cause fever(oft blamed on roid flu). That's why it's called a pyrogen(fever causing agent).
And I totally agree that Homebrewers should use facriry sealed Sterile and depyrogenated vials as opposed to go through the process of cleaning, rinsing sterilizing and depyrogenating the vials and the headache of the stoppers as well.
However I disagree they shouldn't syringe filter directly into the sealed Sterile vial bc as you said - that cuts air out of the equation as long as one uses a syringe filter on their vent needle.
Just as hormone powders go into solution and filter through - any pollutants that go into solution and exo and Endo toxins will filter through also.
If it's a matter of matching my information with what you believe: then please don't take my word for it - research it. I only wish to save the Homebrewers from problems. I don't sell one thing online so I don't care about competition. Please by all means look deep into what I'm saying. Also there is an amount of bacteria BA won't kill bc BA I'd made to stop the growth of bacteria faster than it reproduces not bacteriocidal as much as bacteriostatic.
More general info: gram negative bacteria loves water. So water is a big problem in combating Endo toxins from gram negative bacteria in the production of parenterals in the pharmaceutical industry.
Good Luck Homebrewers!
Cover as you mix and heat your solution - and sterilize and depyrogenate your BEAKERS or pyrex glass measuring cups - which can also be used. And heat 250 for at keast 15 minutes to deactivate Endo toxins.
Research it. Don't believe - look and see for yourself - don't trust me or him. Research it.