Reconstitution

Reconstitution is the lab procedure in which a lyophilized peptide is dissolved in a solvent to give a solution of defined concentration. The maths is a single division: mass in the vial over volume of solvent. Dissolving a 5 mg vial in 2 mL yields 2.5 mg/mL, or 2,500 mcg/mL, so 0.1 mL of the solution holds 250 mcg of peptide. This is a concentration calculation for working with research material and not an instruction for human administration.

Technique

Run the solvent slowly down the inside wall of the vial so that it flows onto the cake instead of hitting it as a jet, then let it dissolve or swirl it gently. Shaking hard creates shear and air–liquid interfaces, and both can make delicate sequences aggregate. Most freeze-dried research peptides go into solution within a few minutes; hydrophobic sequences may need a little organic co-solvent before they are diluted into an aqueous buffer.

Getting the basics right

Every later step relies on a correct, recorded concentration. The choice of solvent governs how long the solution remains usable: bacteriostatic water contains benzyl alcohol and is suited to vials that will be sampled repeatedly, whereas sterile water contains no preservative and is suited to single-use preparations. Mark the vial with concentration, solvent and date.

Related terms

aliquot · stability. See the step-by-step reconstitution guide, the reconstitution calculator, and reconstitution supplies.