Reconstitution and storage: a practical lab guide
Lyophilised peptides are stable and forgiving while they are dry and sealed. Almost every avoidable loss of material happens in the few minutes around reconstitution, or in the weeks afterwards through poor labelling and repeated freeze-thaw. This guide sets out the handling routine we use in our own lab. It is a laboratory-practice note, not a protocol, and it contains no dosing guidance of any kind.
Before you open the vial
Take the sealed vial out of the freezer and let it sit until it reaches room temperature. Opening a −20°C vial in a warm room draws condensation straight onto the cake, and water introduced that way is not measurable, which means your final concentration stops being a number you can defend. Fifteen to twenty minutes on the bench is usually enough for a standard 3ml vial.
While it warms, write the label you are going to need: compound, lot number, diluent, target concentration and date. Doing this first sounds fussy, but an unlabelled reconstituted vial is effectively scrap.
Choosing a diluent
Diluent choice follows your protocol and the solubility behaviour of the specific sequence, not a house rule. Bacteriostatic and sterile waters are the common laboratory defaults; some sequences with poor aqueous solubility need a small volume of a co-solvent before aqueous dilution. If a compound is new to your bench, run a small-volume solubility check before committing a full vial.
Adding the diluent
- Direct the stream against the glass wall, not onto the cake — a jet of liquid straight into lyophilised powder shears peptide chains.
- Add slowly. A vial that takes thirty seconds to fill will dissolve better than one filled in three.
- Swirl, never shake. Foaming is a visible sign of denaturation at the air-liquid interface.
- Give it time. Some sequences take several minutes to go fully clear; warmth and agitation are not the answer.
Storage after reconstitution
Once in solution, peptides are far less stable than they were dry. Refrigerated storage is the norm for short working windows, and freezing is reserved for stock you genuinely will not touch for a while. Whatever window your protocol specifies, respect it and write the date on the vial.
Freeze-thaw cycles
Each freeze-thaw cycle costs you material and adds variability. If a reconstituted stock will be drawn on repeatedly, aliquot it once into single-use volumes rather than returning the same vial to the freezer again and again.
Light and headspace
Amber vials or a foil wrap protect light-sensitive sequences. Keep caps sealed; repeated venting exchanges the inert headspace for humid room air.
Keeping results traceable
Every vial we ship carries a lot number, and a certificate of analysis for that exact lot is available on request. Carry the lot number through into your own records at the point of reconstitution. When a result later looks anomalous, being able to tie it back to a specific batch is the difference between a diagnosable problem and a discarded dataset.
A note on scope
Everything we supply is for in-vitro laboratory research. Our products are not medicines, hold no licence for human or veterinary use, and nothing above should be read as suggesting administration to people or animals.