Peptide Reconstitution Guide

Sealed vial of lyophilised peptide, bacteriostatic water (0.9% benzyl alcohol), calibrated pipette or graduated measuring device, alcohol wipes, and a clean working surface.

Wipe both stoppers with alcohol. Draw your target volume of bacteriostatic water into the syringe. Add it down the side wall of the peptide vial slowly — never directly onto the powder. Swirl gently to dissolve. Do not shake. Refrigerate.

Concentration = peptide mass ÷ reconstitution volume. Example: 5 mg peptide ÷ 2 ml water = 2.5 mg/ml. Record the concentration on the vial label.

Bacteriostatic water — sterile water with 0.9% benzyl alcohol — is the default vehicle because the preservative keeps a multi-use vial usable across repeated draws from the same vial. Sterile water without preservative is appropriate for single-use preparation where the entire contents are used immediately. Acetic acid solutions serve sequences that dissolve poorly at neutral pH; the choice between vehicles comes from the reference method for the compound, not from preference.

One mechanical point causes most reconstitution problems: solvent should be directed down the vial wall rather than streamed onto the powder cake, and mixing should be a gentle roll or swirl rather than shaking. Foaming and shear stress are the enemies of peptide solutions; patience is the cheapest instrument in the protocol.

The relationship researchers need is simple: concentration equals mass divided by volume, and every practical decision — how much solvent to add, what a draw contains — follows from it. The reason it still goes wrong in practice is unit drift between label conventions, which is why the reconstitution calculator works in milligrams and millilitres only, with a visual syringe showing where the plunger should sit on a 1 ml syringe.

Two habits keep the arithmetic honest. First, work from the actual batch certificate's net content, not the nominal label value — residual water means they can differ slightly. Second, decide the target concentration before opening the vial, and add the calculated volume in one motion; incremental additions multiply measurement error.