Technical library
Reconstitution concentration calculator
Concentration is mass divided by volume. It is simple arithmetic that is easy to get wrong at three in the afternoon, so here it is as a tool.
Enter a mass, a diluent volume and a draw volume.
This is arithmetic for laboratory preparation. It is not dosing guidance, and nothing supplied by White Label Peptides is for human or animal use.
The maths
What the tool is doing
Three numbers determine everything. The mass in the vial is fixed at fill and does not change. The diluent volume is chosen at reconstitution. The draw volume is chosen at the point of use.
Concentration is the first divided by the second. A 10 mg vial reconstituted with 2 mL of diluent gives 5 mg/mL. The same 10 mg vial reconstituted with 1 mL gives 10 mg/mL, which is twice the concentration from an identical vial. Nothing about the compound changed. Only the water did.
The mistake worth avoiding. Two vials with identical labels can produce draws that differ by a factor of two or more, purely because a different diluent volume was used. If a procedure specifies a mass rather than a volume, the diluent volume has to be recorded alongside it or the record is not reproducible.
Working in micrograms
Concentrations are usually quoted in mg/mL while small draws are more naturally described in micrograms. One milligram is 1,000 micrograms, so a 5 mg/mL preparation contains 5,000 mcg per mL, and a 0.1 mL draw from it contains 500 mcg. The calculator does this conversion so the decimal point does not have to be tracked by hand.
Why the certificate matters here
Every figure above depends on the mass actually present in the vial being the mass you think is present. That is what the batch Certificate of Analysis establishes. A calculator applied to an assumed mass produces a confident number that is wrong, which is worse than no number.
Questions
About this calculator
What does this calculate?
Concentration. You give it the mass in the vial, the volume of diluent added, and the volume you intend to draw. It returns the resulting concentration in mg per mL, the mass contained in that draw volume, and how many draws of that size the vial yields.
Why does it not show syringe units?
Because syringe unit markings exist to measure a dose for administration, and nothing we supply is for administration. The underlying arithmetic is the same either way: concentration is mass divided by volume.
Does the diluent volume need to be exact?
For concentration maths, yes, because concentration is entirely determined by it. Adding 1 mL rather than 2 mL to the same vial doubles the concentration of every draw taken from it.
Does reconstitution change the mass in the vial?
No. The mass is fixed at fill. Diluent volume changes only how that fixed mass is distributed through the liquid, which is why the same vial can present as two very different concentrations.
What figure should I use for the mass?
The mass stated on the batch Certificate of Analysis for the vial in front of you, not the nominal figure on a catalogue page. Those are usually the same and occasionally are not.
Supply enquiries
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