I know this was your original point but this is way more effort than its worth and harder to get right than it would seem. As people know benzyl alcohol doesn’t sterilize anything, it only slows bacterial growth, so if anything gets contaminated during mixing, filtering, or vialing, you’ve just sealed bacteria into every vial. Measuring sub-milliliter BA accurately is difficult and being off even a little can mean it’s either no longer bacteriostatic or unnecessarily irritating to inject. Not directed at you but.. People are cheap as fuck, just pay the $10-$12 for hospira.