Switching peptide suppliers: a requalification walkthrough

Treat the switch as a change, not a reorder

This guide is about how to change suppliers, not which supplier is better. The risk in a switch is rarely the new material alone; it is that results produced before and after the change can no longer be compared because nobody recorded what differed.

ICH Q7 says a change in the source of supply of critical raw materials should go through change control. [1] Its change-control section recommends written procedures to identify, document, review and approve changes, an assessment of the potential impact on quality, and a classification such as minor or major to decide how much testing and documentation the change needs. [1] A research lab can apply the same logic with a one-page change record: what is changing, why, what could differ, what will be checked, who approves.

Open the change record before ordering from the new supplier, and keep enough of the old material, if you can, to run a side-by-side comparison.

Step 1: collect the new supplier's documents

Run the new supplier through your normal approval route, usually at conditional status. Ask for a lot-matched certificate that names the material and grade, gives the batch number and release date, lists each test with limits and numerical results, and is dated and signed; if the seller is not the manufacturer, ask for the original manufacturer's name and certificate. [1]

Ask also for the traceability records Q7 lists for distributors, including the manufacturer's batch number and the retest or expiry date, and for the SDS. [1] Collect the same document set you hold for the incumbent so the comparison in step 2 is like for like.

Step 2: run a bridging comparison

Lay the last released lot from the old supplier and the first lot from the new supplier side by side. Most of the comparison is on paper: the two certificates, the order specifications and the labels. Where the paper leaves a gap, a test fills it. Q7 recommends at least one identity test on each batch of incoming material [1], and FDA's drug GMP rule requires at least one identity test on each component even where a supplier's report of analysis is accepted. [2]

Watch the attributes that change silently between suppliers. Two vendors can both describe a peptide as 98 percent pure while one reports acetate salt and the other trifluoroacetate, or one reports net peptide content and the other does not, so the same weighed mass contains different amounts of peptide. The purity versus content and salt form guides on this site explain those quantities.

Step 3: evaluate the first lots under the new source

Q7 recommends evaluating the first batches produced or tested after a change is implemented. [1] For a supplier switch that means tighter checks on the first few lots: certificate matched to lot every time, an identity check on each, and a note of any result that looks out of line with the old supplier's history.

Q7 also recommends complete analysis on at least three batches before reducing in-house testing of a new supplier's material, with periodic complete analysis afterwards compared against the supplier's certificates. [1] Few research labs run full analysis that often, but the three-lot idea is a reasonable trigger for moving a supplier from conditional to approved.

Step 4: update every document that names the old supplier

Q7 recommends that, when an approved change is implemented, every document affected by it is revised. [1] Search for the old supplier's name and catalogue numbers rather than relying on memory.

• Approved supplier list: new supplier conditional, old supplier status and end date
• Procurement SOP and order templates that name a supplier or catalogue number
• Inventory and receiving logs: new lot entries, old lot remaining stock
• Test methods or worksheets that assume a salt form or content value
• Methods-section text for papers in preparation: supplier, catalogue and lot
• Budget sheets and standing quotes

Step 5: close the old account without losing records

Closing an account is not the same as discarding its paperwork. ISO/IEC 17025 clause 8.4 expects controlled retention and disposal of records and retention consistent with contractual obligations [3], and federal awards carry a three-year retention period from the final financial report under 2 CFR 200.334. [4] Keep the old supplier's file, certificates and change record together, marked as historical.

Keep any remaining old-lot stock clearly labelled and separate. Q7 recommends that incoming material be identified, tested if appropriate and released before it is mixed with existing stock [1]; in a research lab, simply never combine vials from different suppliers or lots. Finally, cancel standing orders and saved payment details with the old supplier so nobody reorders by habit.