help me understand mg/mL, I have read the wiki twice
help me understand mg/mL, I have read the wiki twice. I would rather ask a basic question now than get this wrong quietly for two months.
Reconstituted at 3mL when I meant to use a different volume. Caught it because the units looked wrong on the barrel. Now I write 5mg/mL on the glass before I put the cap back.
I keep a laminated card in the drawer with the arithmetic on it. Looks ridiculous. Has never once let me draw the wrong volume.
Shook the first vial because nobody told me not to. It was fine, but I have swirled every one since.
Screenshot none of this. Read the whole thread, including the parts where I am told I am wrong.
best — the order this archive was captured in
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.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
Wrote the date on the vial as well as the concentration after losing track of which one was opened first.
Small fix — a U-100 syringe is 100 units per mL. If yours is marked differently it is not U-100 and the whole calculation changes.
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.
What is written on the vial right now?
swirl, never shake
10mg into 2mL is 5mg/mL, and 0.5mg of that is 10 units
That only works if the fill weight is exactly the label weight, and it usually is not exactly anything.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
This. Showing the working is the fastest way for somebody else to spot the mistake.
units are a volume on a U-100 syringe, not a dose
label the vial with the date as well as the concentration
Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.
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.
That is sterile water, not bacteriostatic. Same appearance, different product, and it matters for a multi-draw vial.
What concentration did you actually reconstitute at, rather than what did you intend to?
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.
Correction: that gives 20 units, not what you have written. 5mg into 1mL is 5mg/mL and the division follows from there.
Asked JEEP what volume they reconstitute to for their own stability testing and they answered in one line. Useful thing to know.
Left up and flaired Explainer — the numbers in this one check out.
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.
How many mg in the vial and how many mL are you adding?
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 15mg/mL on the vial takes four seconds and removes the entire class of error this board exists to fix.
- 1Disagree with the "more water is safer" framing. It is not safer, it is just…9 comments in this branch · started by u/escrow_evangelist