I've shifted my ideal somewhat for oils. .22um into a vial FDA certified free of particulates, then a vented spike to prevent coring. Filtered would be preferable, but I think an unfiltered spike would be acceptable.
For peptides, personally, for me I'm shifting to per dose filtration. After reconstitution, pull the entire vial into a 3ml syringe. Attach 13 or 25mm filter, attach needle, each dose is backfilled into an insulin syringe as needed. I store the 3ml syringe/filter/needle setup in a container in the fridge.
I've ordered syringes more compatible with storing peptides, ie, free of silicon.
Bit of a learning curve (ie, backfilling from a needle vs the open end of the filter is much easier), but happy with the results so far.
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