Storage & Handling Guide
Keeping compounds stable
Degradation is not one process but four, with different chemistry and different countermeasures. Reading a handling note is largely a matter of identifying which of the four it is guarding against — because the instruction names the threat.
- Lyophilised
- −20 °C, dark
- Reconstituted
- 2–8 °C
- Freeze-thaw
- Cumulative damage
- Interval
- Per certificate
Four states, four rules
A vial passes through each of these, and the handling changes at every step.
- 01Lyophilised, sealed−20 °C
The stable state. Water has been removed, so hydrolysis, deamidation and oxidation all proceed orders of magnitude more slowly. Protect from light and moisture.
- 02In transit2–8 °C
Acceptable short-term for lyophilised material under insulated cold chain. If an in-transit indicator arrives out of range, tell the desk before opening the vial.
- 03Reconstituted2–8 °C
The protection lyophilisation provided has been deliberately reversed. Observe the interval stated on the batch certificate — it is compound-specific, not general.
- 04Aliquoted−20 °C, one thaw
Where a preparation will be drawn on more than once, aliquot at the moment of reconstitution. Repeated freeze-thaw cycles aggregate peptide chains cumulatively.
What actually degrades a compound
Four pathways, four triggers. Handling advice that treats every compound alike protects against the average threat and the specific one badly.
Degradation is not one process but four, with different chemistry and different countermeasures. Reading a compound's handling note is largely a matter of identifying which of the four it is guarding against — because the instruction names the threat.
Hydrolysis
Cleavage of the backbone by water, accelerated by temperature and by pH excursion in either direction. It is the reason lyophilised storage exists at all. Countermeasure: keep water out; once in solution, keep it cold and near neutral unless the compound documents otherwise.
Oxidation
Methionine, cysteine and tryptophan are susceptible to dissolved oxygen, accelerated by light and by trace metal ions. Compounds carrying a metal centre have an additional exposure. Countermeasure: minimise headspace, work in subdued light, avoid reducing agents and chelators.
Deamidation
Asparagine and glutamine convert to acidic counterparts through a cyclic intermediate, producing a molecule one dalton heavier with an altered charge state. Strongly pH-dependent, and one of the quiet reasons diluent choice belongs in the record.
Aggregation
A physical rather than chemical change: molecules associating into higher-order structures, driven by concentration, agitation and exposure at an air-liquid interface. This is the mechanism behind swirling rather than shaking.
| State | Temperature | Light | Typical window |
|---|---|---|---|
| Lyophilised, sealed | −20 °C | Protected | Per retest interval on certificate |
| Lyophilised, in transit | 2–8 °C acceptable short-term | Protected | Days |
| Reconstituted | 2–8 °C | Protected | Per interval stated on certificate |
| Reconstituted, aliquoted | −20 °C, single thaw | Protected | Per interval; one thaw only |
This guide is educational and describes general laboratory handling. Stability intervals are compound-specific and stated on the certificate of analysis for each batch rather than generalised across the catalogue. This catalogue is presented for informational purposes only. It is not an offer of sale, and it makes no medical or therapeutic claim.
Enquiries
An indicator arrived out of range?
Tell the desk before opening the vial. Custody questions are answered against the actual dispatch record rather than a general policy.