Been going back and forth on this for weeks and want to hear from people who actually filter.
My setup: reconstitute in the original vial (0.5-2mL bac water depending on the peptide), draw the full contents into a 3mL Luer Lock syringe, attach a 13mm PES 0.22um filter, attach a fresh 21G on the output side, push through into a sealed 5mL sterile receiving vial (ALK).
My biggest transfer is about 2.15mL into a 5mL vial. That is less than half the vial's air space.
I keep seeing people say you need a vent needle in the receiving vial to let displaced air escape while you push liquid in. Some people use a plain 18G, some say you need a filtered 0.2um hydrophobic vent, and those things are either impossible to source as an individual or cost $300+ each.
But if I am only pushing ~2mL into a 5mL vial, is the back-pressure actually a problem? It seems like the air just compresses a bit and the syringe plunger handles it fine. Has anyone here actually tried filtering into a sealed 5mL vial without any vent at all?
If you do use a vent, are you using a plain open needle or a filtered one? And if plain, does that not defeat the entire purpose of filtering since you just gave room air a direct path into the vial you are trying to keep clean?
Genuinely trying to figure out the right move here.
Appreciate any real experience.