[Meta] proposal — a flair for units posts
proposal — a flair for units posts, and it will stay as it is unless somebody makes the case to change it.
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
Research-use-only material is not approved for human use, so treat everything in this thread as arithmetic about solutions rather than instructions for a person.
Reconstituted at 1mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 20mg/mL on the glass before I put the cap back.
Ask me anything specific. Anything general I will probably get wrong.
best — the order this archive was captured in
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.
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.
Cosigning the round-number approach.
Adding one thing — put the date on the label too. Concentration plus date and you can never mix two vials up.
How many mg in the vial and how many mL are you adding?
more water is not more drug, it is the same drug in a bigger volume
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
the powder cake sits at the bottom, the volume you add is the volume that counts
Aim the stream down the wall of the vial rather than into the cake. Reconstitution is a solubility problem, not a mixing problem, and mechanical shear does nothing helpful.
The dead space question sent me down a rabbit hole for a week. It is a fraction of a unit and it is the same every draw.
[removed by moderator]
That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
Aim the stream down the wall of the vial rather than into the cake.
This is the sentence that makes the rest unnecessary. Write it on the vial and the problem is gone.
Asked GGPeps what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
Working has to be shown on arithmetic posts. Added a note asking for it rather than removing this one.
Bacteriostatic water contains benzyl alcohol as a preservative, which is what makes repeated entry into the same vial reasonable. Plain sterile water has no preservative.
a U-100 syringe reads 100 units to the millilitre, every time
Working has to be shown on arithmetic posts.
Right, and the arithmetic behind it: 30mg in 3mL is 10mg/mL, so 2.5mg is 25 units.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
Spent 13 weeks confused about this until somebody drew the table for me. 15mg, 3mL, 5mg/mL, 0.5mg is 10 units. That is the whole thing.
Working has to be shown on arithmetic posts.
bac_water_bandit has the units point exactly right. They are a volume on the barrel and nothing else.
I would not round that figure. At 5mg/mL a rounding error of two units is a real fraction of the intended amount.
- 1Asked GGPeps what volume they reconstitute to for their own stability…9 comments in this branch · started by u/sock_puppet_spotter
- 2Adding more water does not change how much peptide is in the vial. It…7 comments in this branch · started by u/viktor_erdogan