How to reconstitute peptides: the full walkthrough.

What you need before you start

Three items cover the whole procedure. First, bacteriostatic water, ₱250 for a 30ml bottle. This is sterile water with 0.9% benzyl alcohol, a preservative that suppresses bacterial growth in an opened vial. Plain sterile water has no preservative, which is why it is not the standard for multi-access vials. Second, a sterile insulin syringe, U-100, 1ml. It transfers the water and later measures draws. Third, alcohol prep pads for the rubber stoppers on both vials. All of this fits in a drawer, and the full list lives in the lab supplies checklist.

The procedure, step by step

Wipe both stoppers with an alcohol pad and let them dry. Draw your chosen volume of bacteriostatic water into the syringe. Pierce the peptide vial stopper at an angle and aim the stream at the glass wall, not at the powder cake. Letting the water run down the inside of the vial dissolves the cake gently. Depress the plunger slowly, over ten seconds or more, then withdraw the needle.

Now the part that gets done wrong most often: do not shake. Peptides are chains of amino acids held in a specific structure, and the shear forces from vigorous shaking, plus the foam it creates, can aggregate or denature the material. Swirl the vial gently or roll it between your palms. Most compounds dissolve into a clear solution within a minute or two. A few can take longer. If a slight haze persists after several minutes of gentle swirling, let the vial sit refrigerated and check it again later before judging it. Once dissolved, write the date and the concentration on the label and move the vial to the refrigerator, 2 to 8°C. The working window from that point is covered in the shelf life guide.

The concentration math

The volume you add fixes the concentration, and the concentration fixes what each syringe unit contains. The core formula: milligrams in the vial divided by milliliters added equals milligrams per milliliter. A 10mg vial with 2ml of bacteriostatic water gives 5 mg/ml. On a U-100 insulin syringe, one unit is 0.01ml, so at 5 mg/ml each unit holds 50 micrograms. Add 1ml instead and the same vial reads 10 mg/ml, or 100 micrograms per unit. Neither is more correct. More volume simply spreads the material across more units, which makes small quantities easier to measure precisely. Worked examples for every vial in the catalogue are in the reconstitution math post. One 30ml bottle of bacteriostatic water covers well over a dozen vials at typical volumes, so a single bottle added to a compound order usually lasts months.

Supplied for laboratory research use only. Not for human consumption. Nothing on this page is medical advice.