[Question] how do you actually verify bacteriostatic water
The title is the whole question — how do you actually verify bacteriostatic water — but here is why I am asking.
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.
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.
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.
If somebody has the same thing measured a different way, post it next to mine and we will see whether they agree.
best — the order this archive was captured in
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.
Disagree with the "more water is safer" framing. It is not safer, it is just a different number to divide by.
How many mg in the vial and how many mL are you adding?
write the concentration on the vial in marker, that is the whole post
Left up and flaired Explainer — the numbers in this one check out.
Why "more water" keeps confusing people, including me for a month.
The vial contains a fixed amount of peptide. Water changes nothing about that amount. What it changes is concentration, and concentration is the divisor between the dose you want and the volume you draw.
So doubling the water halves the concentration and doubles the units for the same dose. Nothing is diluted in any sense that matters; you are simply reading a bigger number off the same barrel. Pick the water volume that puts your usual dose on a whole number of units and life gets easier.
a U-100 syringe reads 100 units to the millilitre, every time
aim the stream at the glass wall, not at the cake
Cosigning the round-number approach. Reconstituting to something awkward is how you end up drawing 27.5 units at six in the morning.
Yes, and the dead-space point is worth repeating: it is small, it is real, and it is the same for every draw.
Not quite. Bacteriostatic and sterile water are not interchangeable for a multi-draw vial, and the difference is the preservative.
reconstituting at a round concentration makes every later dose easy
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.
Did the maths give you a whole number of units, or a fraction?
twice as much water halves the concentration and doubles the units for the same dose
Is that a U-100 syringe? The barrel markings change the answer completely.
20mg into 2mL is 10mg/mL, and 2mg of that is 20 units
The arithmetic in full: concentration is mass over volume, so 30mg into 3mL gives 10mg/mL. A U-100 syringe is graduated at 100 units per millilitre, so 2mg is 2 divided by 10 millilitres, which is 20 units.
Agreed on the swirl. There is no reason to shake it and a good reason not to.
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.
if the maths gives you a fraction of a unit, change the concentration
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.
Show the arithmetic — where did the unit figure come from?
Pushback on the syringe advice: a U-100 barrel reads units of volume. Calling them "doses" is how the confusion starts.
Correction: that gives 100 units, not what you have written. 15mg into 3mL is 5mg/mL and the division follows from there.
label the vial with the date as well as the concentration
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.
units are a volume on a U-100 syringe, not a dose
- 1Show the arithmetic — where did the unit figure come from?6 comments in this branch · started by u/signe_grimaldi