Storage and Handling

Why compounds ship lyophilised

Lyophilisation — freeze-drying — removes water by sublimation under vacuum, leaving a dry cake. Water is what most degradation pathways need: hydrolysis of the peptide bond, deamidation of asparagine and glutamine residues, and oxidation of methionine and cysteine all proceed far more slowly in a dry solid than in solution.

The practical consequence is that a lyophilised vial is stable at room temperature for the days a domestic parcel is in transit, and does not need a cold chain to arrive intact. It is also why the vial is sealed under vacuum or inert gas: breaking that seal admits atmospheric moisture, and the cake will take it up.

Before reconstitution

• Long-term: −20°C, in a dry, dark environment, sealed. A standard laboratory freezer is sufficient; −80°C buys little for a dry solid.
• Short-term: 2–8°C or room temperature is acceptable for weeks rather than months, which is what makes shipping possible.
• Let a cold vial reach room temperature before opening it. Opening a vial straight out of a freezer condenses atmospheric moisture onto the cake, which is the single most common way a dry compound is spoiled before it is ever used.
• Keep it dark. Several compounds — the melanocortin analogues in particular — are photosensitive.

After reconstitution

Reconstitution puts the compound back into the conditions lyophilisation removed it from, and the clock starts. Bacteriostatic water (water with 0.9% benzyl alcohol) is the usual diluent for laboratory work because the preservative suppresses microbial growth; sterile water without a preservative does not, and a vial reconstituted with it is a single-use preparation.

• Store at 2–8°C and use within the window stated on the product page — 30 days is typical across this catalogue, and some compounds are shorter.
• Do not freeze and thaw repeatedly. Each cycle concentrates solutes at the ice boundary and mechanically stresses the molecule. If a solution must be frozen, aliquot it first so each portion is thawed once.
• Add diluent down the vial wall, not onto the cake. A jet directed at the cake shears the material and foams the solution; proteins denature at an air–liquid interface.
• Swirl, do not shake. For the same reason. Give it time rather than agitation — most cakes dissolve within a minute or two.

What degradation looks like

A dry cake that has taken up moisture may appear collapsed, shrunken, sticky or discoloured rather than as a uniform white or off-white solid. A reconstituted solution should be clear; cloudiness, visible particles or a precipitate that does not redissolve indicates aggregation or contamination. None of these are recoverable states — a compound that has aggregated has not become less pure in a way that settling will fix.

Handling

Treat every compound in this catalogue as a laboratory reagent of unknown toxicity, because for most of them that is exactly what the literature supports. Gloves, eye protection and a ventilated area for handling the dry powder are the baseline; lyophilised material is light and aerosolises easily when a vial is opened sharply. Dispose of material and sharps through your institution’s regulated waste stream.

For laboratory research use only. Not for human or veterinary use.