Reconstitution is the laboratory step of dissolving a lyophilized peptide in a solvent to produce a solution of known concentration. The arithmetic is simple division: vial mass divided by solvent volume. A 5 mg vial taken up in 2 mL gives 2.5 mg/mL, which is 2,500 mcg/mL; 0.1 mL of that solution therefore contains 250 mcg of peptide. This is a concentration calculation for handling research material, not a human administration instruction.
How it is done
Solvent is added slowly down the inner wall of the vial so it runs onto the cake rather than jetting into it, then the vial is left to dissolve or swirled gently. Vigorous shaking introduces shear and air-liquid interface, both of which can aggregate sensitive sequences. Most lyophilized research peptides dissolve within minutes; hydrophobic sequences may need a small amount of an organic co-solvent before dilution into aqueous buffer.
Why it matters
Everything downstream depends on getting the concentration right and recording it. Solvent choice determines how long the solution stays usable: bacteriostatic water contains benzyl alcohol and suits multi-draw vials, while sterile water has no preservative and suits single-use preparation. Label the vial with concentration, solvent and date.
Related terms
aliquot · stability. See the step-by-step reconstitution guide, the reconstitution calculator, and reconstitution supplies.