A supplier questionnaire describes intentions. A quality agreement assigns responsibility when something changes or fails. During a research peptide supplier quality agreement audit, I look for operational detail: who approves specifications, who samples the batch, which laboratory owns the raw data, how subcontractors are controlled, and how quickly the buyer learns about a deviation. A polished certificate cannot compensate for responsibilities left undefined.
Put the product definition in controlled documents
The agreement should point to an approved specification containing sequence, terminal modifications, salt form, theoretical mass, purity method, net-content basis, water, counterion, residual solvents, packaging and storage. Catalogue names are insufficient. If a custom peptide changes from trifluoroacetate to acetate, that is not a clerical edit; it changes the material definition and testing.
Define document precedence. The signed specification should override a sales quotation, web page or generic COA template. Revision numbers and effective dates prevent the supplier from testing against an old limit after procurement has approved a new one.
Sampling is part of the result
State whether release samples come from the bulk container, beginning/middle/end of a filling run, or finished packaged units. Identify who selects them and how retains are stored. A third-party laboratory result is only as representative as the sample submitted. Supplier-selected vials can hide subdivision problems.
For first lots, reserve the buyer’s right to select sealed units independently. Set retain quantity and retention period long enough to investigate complaints near the retest date.
Raw data and laboratory control
List required raw records: complete HPLC chromatograms, integration tables, method conditions, LC-MS spectra, calculations and instrument identifiers. PDF screenshots are not equivalent to original electronic data. Define turnaround for a raw-data request and the conditions under which the buyer may contact the contract laboratory.
If testing is subcontracted, the manufacturer should qualify the laboratory and notify the buyer before changing it. Accreditation alone does not prove that a particular peptide method lies within the laboratory’s competence or scope.
Change control must be specific
Require prior approval or notification for changes in synthesis site, resin, protected amino-acid source, critical reagents, purification method, salt exchange, lyophilization cycle, analytical method, laboratory, fill site, vial, stopper or packaging. Set a risk-based notice period and data package. “Equivalent supplier” is not a sufficient rationale for a material used in batch trending.
Emergency changes may occur, but the agreement should require documented assessment and retrospective buyer communication. Silent changes are a common cause of unexplained impurity and solubility shifts.
Deviations, OOS and reprocessing
Define out-of-specification investigation, out-of-trend review and buyer notification timelines. The supplier should not retest repeatedly until a passing result appears. Original and repeat results, hypotheses and root-cause evidence must remain visible.
Reprocessing—additional purification, salt exchange or drying—requires an approved pathway and full relevant retesting. A new COA that omits the first failure destroys context. The buyer should approve disposition when the deviation can affect the agreed use.
Traceability and complaints
One lot identifier should connect synthesis, purification, bulk storage, filling, labels, COA and shipment. Define reconciliation of bulk mass and finished units. Complaint handling should preserve samples, courier records, temperature data and chain of custody.
Recall language is still useful for RUO supply. It establishes contact lists, scope decisions, customer notification and document retrieval if mislabeling or serious contamination is discovered.
Audit evidence worth requesting
- One completed batch record with confidential details redacted.
- A deviation and change-control example showing closure quality.
- Supplier and testing-laboratory qualification records.
- Equipment calibration, data review and access-control procedures.
- Label reconciliation and batch-to-vial traceability.
- Business continuity and cold-chain excursion response.
Does every small order need a lengthy agreement? The detail should match risk and spend, but the critical responsibilities still need written acceptance. A two-page technical schedule can be more useful than twenty pages of generic legal language.
Before approving a wholesale supplier, run the agreement against a realistic failure: an MS mismatch, a late impurity, or vials testing below bulk content. If the document does not say who investigates, what data are shared and who decides disposition, it is not yet protecting the purchase.