---
title: "What is the difference between a retest date and an expiry date? | Sable Peptides"
description: "The difference between a retest date, an expiry date and a manufacture or test date on a peptide certificate, how ICH Q7 and Q1A define them, and what a buyer should record. Research use only."
canonical: https://www.sablepeptides.co.uk/guides/retest-date-vs-expiry-date-on-a-coa
dateModified: 2026-10-16
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

# What is the difference between a retest date and an expiry date?

A retest date is when a material should be tested again before use; if it still meets specification it can be used. An expiry date is a fixed limit after which the material should not be used. ICH Q7 defines both for active substances. Many research peptide CoAs show only a test date, which is neither.

## How do the dates compare?

| Date | Meaning | Can it be extended? |
| --- | --- | --- |
| Manufacture date | When the lot was made | No |
| Test (analysis) date | When the CoA results were obtained | No; a new test gives a new date |
| Retest date | Re-test before use after this date | Yes, if re-testing passes |
| Expiry date | Do not use after this date | No |

Source: [ICH Q7 Good manufacturing practice for active pharmaceutical ingredients](https://database.ich.org/sites/default/files/Q7_Guideline.pdf); [ICH Q1A(R2) Stability testing of new drug substances and products (EMA)](https://www.ema.europa.eu/en/ich-q1a-r2-stability-testing-new-drug-substances-drug-products-scientific-guideline)

## Why do substances get retest dates?

ICH Q7 notes that many active substances are stable enough to be assigned a retest date rather than an expiry date, because a fresh test can confirm their quality. Products made from them usually carry expiry dates instead. For a lyophilised research peptide, a retest approach makes sense: an HPLC and MS run shows whether the lot is still within specification.

## What should a lab record?

-   The lot number printed on the vial.
-   The CoA test date and any retest or expiry date.
-   The date received and the storage conditions since receipt.
-   The date a vial was first opened or reconstituted.

## Does a test date guarantee current quality?

No. It describes the lot when tested. Storage conditions since then, especially moisture and temperature excursions, determine its state now. 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.

## Frequently asked questions

### Can a material be used after its retest date?

Only after it has been re-tested and found to meet specification.

### Can an expiry date be extended?

Not for the same material under the same label; expiry is a fixed limit.

### Is a CoA test date the same as an expiry date?

No. It records when the analysis was done.

## Related

-   [Stability study terms](/guides/ich-q1a-stability-study-terms)
-   [Lot numbers and traceability](/guides/lot-numbers-and-traceability-in-research-supply)
-   [Peptide stability and shelf life](/learn/peptide-stability-and-shelf-life)
-   [Reserve and retention samples](/guides/reserve-and-retention-samples-explained)
-   [CoA vs CoC: what must a certificate of analysis contain under ICH Q7?](/guides/coa-vs-coc-what-ich-q7-requires-on-a-certificate)

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)

-   Retest date: re-test before use; extendable if passes
-   Expiry date: fixed use-by limit
-   Sources: ICH Q7, ICH Q1A(R2)
-   Updated 2026-10-16