Traceability is the ability to answer two questions in both directions. Given a vial, what is known about it. And given a lot that turns out to be in question, everywhere it went.
The second question is the one that exposes whether records are real. It is also the one nobody asks until it matters.
What the lot number carries
The lot number is the only identifier that ties physical material to its documentation. The compound name does not, because a facility may hold several lots of the same compound at once. The order number does not, because an order may span multiple lots and a lot may span multiple orders.
Everything downstream, the certificate of analysis, the storage record, the aliquot labels, the experimental record, hangs off that one string.
A minimum viable record
A record that supports both directions of lookup holds the following per lot.
- Compound, strength and lot number.
- Supplier and order reference.
- Date received, and condition on receipt including any cold chain observation.
- The certificate of analysis for that lot, stored where it can be found rather than in an inbox.
- Storage location and conditions.
- Quantity received, and quantity remaining as it is drawn down.
- Reconstitution events: date, diluent, concentration, who prepared it, and the aliquot identifiers created.
- Disposal: date, quantity and method.
Where chains break
Four failure points recur, and all four are mundane.
- The aliquot without a lot number. A tube labelled with compound and concentration but no lot cannot be traced back to any certificate, which makes the material anonymous regardless of how carefully the original vial was recorded.
- The certificate that lives in an email thread. If retrieval depends on searching one person's mailbox, the record is a single point of failure.
- The partially used vial returned to storage without updating the quantity. Reconciliation then fails and nobody knows whether material is missing or simply unrecorded.
- The informal transfer between benches or sites, where material moves and the record does not.
The reverse lookup test
The honest test of a recordkeeping system is to pick a lot number and try to list, in a few minutes, every aliquot derived from it, every piece of work that used it, and where any remaining material is.
A system that cannot do that is a filing system rather than a traceability system. The distinction only becomes visible when a supplier issues a notice about a specific lot, or when a result is anomalous and the material becomes a candidate explanation.
Retention
Retention periods are driven by the governing framework a facility operates under, by institutional policy, and in some cases by contract terms with funders or partners. There is no single universal period, and the sensible approach is to set a documented policy rather than to default to whatever happens.
Where records relate to work that may be published, reviewed or audited, retaining the certificate alongside the experimental record is the inexpensive option. A certificate is a small file; reconstructing one for a consumed lot years later is often impossible.
Paper, spreadsheet or system
All three work, and the determining factor is not sophistication but discipline.
- A bound notebook is simple and tamper-evident but not searchable, which makes the reverse lookup slow.
- A shared spreadsheet is searchable and cheap, and is adequate for most practices provided it has a single owner and lives somewhere backed up.
- An inventory or laboratory information system adds enforced fields and audit trails, and is worth the overhead at volume or where a framework requires it.
A well-kept spreadsheet beats a neglected system comfortably. The question to ask of whichever is chosen is simply whether the reverse lookup works.
For how this fits with everything else that happens to a vial between delivery and use, peptide storage and handling for clinics covers the full picture.