Most supplier qualification processes fail in the same place: they start with a price request and end with a quality questionnaire attached to an email nobody reads. The sequence below takes about three weeks and replaces that ritual.
1. Start with the regulatory file, not the sample
A sample proves the supplier can make one kilogramme. The regulatory file proves they can support a commercial product in your market. Ask for the open part of the Drug Master File, or the Certificate of Suitability reference where one exists, before any sample is dispatched. If the answer is "we will send it after you order", treat that as a substantive finding.
2. Read the CoA like an auditor, not a buyer
Three things to check on a specimen CoA:
- Are the methods cited? "Assay 99.4%" without a method reference is a marketing number. You need HPLC or titration, with the column and mobile phase described or referenced.
- Are specified impurities listed individually? A total-impurities figure alone hides the impurity that matters to your stability profile.
- Is it a real batch? Ask for a recent commercial batch number and confirm the quantity produced. A CoA for a 50 g laboratory lot tells you very little.
3. Ask what changes between batches
Every manufacturing process has variance. The qualification question is not whether variance exists, but whether you are told about it. Ask directly: do you declare route changes, site changes, and major equipment changes before shipment? The answer should be a reference to a written change-control procedure with a notification clause in the supply agreement.
4. Request the audit pack, then test one claim in it
A full audit pack — GMP certificate, site master file, deviations summary, recall procedure — is a lot of paper. Read it, then verify one specific claim: pick a batch number, ask for the corresponding deviation record, and see whether the story matches the CoA. Suppliers who keep real records answer in a day. Suppliers who do not, answer with a brochure.
5. Only then talk about samples and price
Once the documentation holds up, a qualification sample and a quotation are meaningful. At this point ask for a retained lot: hold material from the same lot for the duration of your laboratory work, so a repeat order three months later still traces back to the batch you tested.
What good looks like in the reply
You are looking for short, specific answers with document references. Long answers that avoid a yes or a no are a signal. A supplier who says "we do not hold a CEP for this product, here is what we do hold" is more useful than one who says "all certificates available".
This note describes general industry practice. It is not regulatory advice and does not replace the requirements of your destination authority or your own quality system.