Two lots can share a product name and still create different formulation outcomes. The useful question is whether each lot meets the same agreed requirements, using comparable methods, and whether changes between lots are visible to the buyer. This matters when a sample is approved first and commercial orders follow months later.
Define the comparison before the first order
Put the material identity, supplied form, analytical methods and acceptance limits in a written specification. Separate critical attributes from descriptive catalog information. For a peptide powder, the relevant set may include identity, chromatographic profile, water or residual solvents, but the exact panel depends on the material and intended application. Do not import another supplier’s purity number without its method and calculation basis.
Compare records, not headline percentages
Match identity and lot references
Record the supplier lot on the pack, COA and receiving record. Check that names, salt form and any premix composition remain consistent. The FDA cosmetic GMP checklist describes identity and lot identification for raw materials and batch records showing the kinds, lots and quantities used in finished cosmetics. That trace is what allows a later investigation to reach the affected finished batches.
Read the underlying method
Compare each result with its method, units and limits. A chromatographic area percentage and an assay of peptide content are different measurements. If a supplier changes an analytical method, request an explanation of comparability before treating a numerical shift as a material change. Ask whether representative chromatograms or other supporting records are available when a result needs investigation.
Track supplier and process changes
Agree which changes require notice: manufacturing site, synthesis route, purification, counter-ion, excipients, packaging or test method. Not every change requires rejection; it does require an assessment against the approved specification and use. Keep the sample qualification decision, later COAs and change correspondence together.
A practical lot review table
- Identity: same defined substance and supplied form?
- Testing: same methods, units and acceptance limits?
- Results: any meaningful trend or new impurity signal?
- Packaging: same container and storage instructions?
- Change history: any notified change needing assessment?
- Disposition: who approved the lot for the intended use?
For cosmetic finished products, ISO 22716:2007 provides GMP guidance on production, control, storage and shipment. Its scope is cosmetics manufacturing; it does not turn a supplier’s sample COA into proof of all later lots. See our COA guide and quality approach for the document review that supports a repeat order.
Frequently asked questions
Must two lots have identical chromatograms?
Not necessarily. Assess differences against validated or agreed methods, defined limits and the intended use, rather than expecting identical traces.
Does a passing COA mean a new lot needs no review?
The COA is central, but receiving checks, lot identity, changes and any project-specific requirements still need review.
When should a supplier report a change?
Put the notification categories and timing in the purchasing agreement before repeat supply starts. Evaluate each reported change against your qualification basis.
A short, signed lot review is easier to use later than an unexplained folder of COAs.