1. On arrival
- Reconcile the lot numbers on the packing note against the vials and against the published certificates before anything goes into the freezer.
- Move lyophilised material to −20 °C promptly. Transit at ambient temperature is accounted for in the stability data, but there is no reason to extend it.
- Do not be alarmed by a vial that looks empty. Two to five milligrams of lyophilised peptide can form an almost invisible film, and material is frequently thrown onto the vial walls in transit. Centrifuge briefly or tap the vial down before opening.
2. Storage of lyophilised material
Sealed at −20 °C, protected from light and moisture, most lines are stable for 24 to 36 months. The retest date on the certificate is the figure to work to.
Always let a vial reach room temperature before breaking the seal. Opening a cold vial draws in warm moist air which condenses onto hygroscopic powder, and water is the main driver of degradation in the solid state.
3. Reconstitution
Each product page states a tested solubility for that compound. Sequences that are hydrophobic or prone to aggregation frequently dissolve poorly at neutral pH and go into dilute acetic acid far more readily.
Add solvent slowly down the vial wall rather than directly onto the plug, and swirl rather than vortex — mechanical shear and foaming both promote aggregation. Choice of solvent, concentration and buffer for your assay is a matter for your own protocol.
4. Material in solution
Peptides are markedly less stable in solution than as a lyophilised solid. The main routes of loss are hydrolysis, oxidation of methionine and cysteine residues, deamidation at asparagine and glutamine, and physical loss through freeze–thaw cycling and adsorption to container walls.
- Aliquot on first reconstitution so no stock is ever thawed twice.
- Store aliquots at −80 °C where available, and in low-binding tubes for dilute solutions.
- Protect methionine- and cysteine-containing sequences from air; consider an inert headspace.
- Note the date of reconstitution on the tube. It is the single most useful thing to have written down when a result looks wrong.
5. Safety
Handle as laboratory chemicals of unknown toxicological profile. Nitrile gloves, safety spectacles and a laboratory coat as a minimum; weigh powders in a fume hood or balance enclosure to avoid inhaling fines.
A safety data sheet accompanies every consignment and is available before ordering on request. Dispose of material and contaminated consumables as laboratory chemical waste through your institution's licensed contractor. Do not discharge to drain.