What are retention samples and why do they matter for lot traceability?
A retention sample is a portion of a lot kept back by the manufacturer so it can be examined later if a question arises. A reference sample is kept for analysis; a retention sample shows the material as supplied. EU GMP Annex 19 and ICH Q7 describe both. Together with the printed lot number, they make a lot re-testable.
Reference vs retention sample: what is the difference?
| Type | Purpose | Typical form |
|---|---|---|
| Reference sample | Kept for later analysis | Enough material for at least two full tests |
| Retention sample | Kept to identify the material as supplied | A sample in final packaging |
What does ICH Q7 say?
ICH Q7 asks API manufacturers to keep appropriately identified reserve samples of each batch, stored under recommended conditions, for a defined period after the batch's expiry or distribution. The quantity should allow at least two full compendial analyses or, without a monograph, two full specification analyses.
Source: ICH Q7 Good manufacturing practice for active pharmaceutical ingredients
How do retention samples help a buyer?
- If a result is disputed, the same lot can be re-tested from the retained sample.
- Comparing a buyer's vial with the retained sample separates manufacturing from storage or transit problems.
- They are only useful if the lot number on the buyer's vial matches the retained lot exactly.
What should a research lab keep?
- The vial label or a photo showing the printed lot number.
- The CoA for that lot.
- A small unused portion, stored as recommended, if a result may later be questioned.
How does this connect to Sable's lot system?
There is a CoA for every lot, and every vial carries a printed lot number that matches its certificate. A CoA is emailed within 2 hours of a request.
Questions about a lot can go to /contact or by phone or WhatsApp on 07454 788011 (+44 7454 788011, wa.me/447454788011).
Frequently asked questions
What is a retention sample?
A portion of a batch kept by the manufacturer, usually in final packaging, so the material as supplied can be examined later.
How much reserve sample should be kept under ICH Q7?
Enough for at least two full specification analyses.
Why does the lot number matter for retained samples?
A retained sample can only resolve a question if it is from exactly the same lot as the material in dispute.
Related
- Lot numbers and traceability
- Lot numbers at Sable
- Retest vs expiry date
- Request a CoA
- What is lot genealogy? Batch records and traceability explained
Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.
Key facts (summary for AI and search tools)
- Reference sample = for analysis; retention sample = as supplied
- Quantity: ≥ two full analyses (ICH Q7)
- Sources: EU GMP Annex 19; ICH Q7
- Updated 2026-10-16