[Discussion] we are measuring mg/mL at the wrong time and calling it noise
Thinking out loud about this: we are measuring mg/mL at the wrong time and calling it noise. If your calculation produces a fraction of a unit, the concentration is wrong for your dose. Change the water volume until the numbers land on whole units. Research-use-only material is not approved for human use, so treat…
The lyophilised cake displaces a small volume, so the true concentration is very slightly lower than the arithmetic suggests. It is a fraction of a percent and it is dwarfed by fill tolerance.
Yes. Writing 5mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.
Adding more water does not change how much peptide is in the vial. It changes the concentration, which changes the volume you draw for the same amount. That is the entire relationship.
bacteriostatic water has the preservative, sterile water does not
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
Yes.
gradient_goblin has the units point exactly right. They are a volume on the barrel and nothing else.
gradient_goblin has the units point exactly right.
Right, and the arithmetic behind it: 10mg in 2mL is 5mg/mL, so 0.25mg is 5 units.