How much head space is in a 3ml pen cartridge
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I want to start using a pen for my rat's peptide research. The current peptide she is researching comes in a 60mg vial that is overfilled to 70mg. According to the handy dandy peptidecritic.com reconstitution calculator, I need to add 3.5ml of BAC water to get to that perfect 20mg/ml ratio. I know a 3ml vial has about 1ml of head space. So how much head space is in a 3ml pen cartridge? Can I put in the entire 3.5ml in or will I have to waste a bit?
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It will be very close, imo. I just did exactly this on Friday and i got almost all of it in the cartridge. Make sure the overflow needle is barely breaking the seal so you don’t get backflow, and depending on hour accurate you are, you may just fill it or have a little extra. I would estimate that I had less than 25-50 units over, which I pushed into another vial, but this assumes my measurements were spot on. Also note that I was moving the liquid from one vial to another for 7 vials, so some small amount of loss likely occurred.
Pic below to show there was 0 air left.
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Thanks Randy. I was wondering what the exact amount was. I guess I had more loss than I thought.
