The practical answer
Match the received container to a lot-specific certificate, then compare identity, analytical methods, purity, content, and document revisions separately. Record missing or conflicting evidence for the laboratory reviewer; a familiar product name or a high purity percentage does not resolve those gaps.
Evidence, method & source dates ↓Start with traceability, not a ranking
When a repeat order arrives with a different lot number, treat it as a new documentation review. Match the label, order, supplier record, and lot-specific certificate before comparing headline percentages. A familiar product name does not establish that the new paperwork describes the container in front of you.
This guide is for laboratory purchasing documentation. It does not determine fitness for a particular experiment, establish medical suitability, or replace the laboratory's quality procedures. No supplier or received lot was independently tested for this article.
Compare like measurements
Bachem's quality-control guide treats identity, purity, and product content as separate questions, supported by different analytical approaches. HPLC peak-area purity and net peptide content should not be treated as interchangeable percentages. A missing measurement remains unknown.
Ask the supplier to identify the method and units behind each reported value. Two certificates with the same headline percentage may not report the same property or use comparable methods. Do not calculate a quality score by averaging unrelated analytical values.
| Record | Compare across lots | Unresolved example |
|---|---|---|
| Identity | Sequence or product specification and identity evidence | Name matches but specification is absent |
| Lot traceability | Container, certificate, and order reference | Certificate names a different batch |
| Purity | Reported method and result | Percentage without method |
| Content | Definition, method, units, and result if supplied | Purity substituted for content |
| Document control | Issue date and revision | Conflicting certificates for one lot |
Write a discrepancy record before deciding
Our recommended receiving worksheet separates what the supplier states, what the reviewer has actually matched, and what still needs clarification. Record the document reference rather than copying unsupported marketing language. Keep the prior lot's certificate as a comparison record, not as evidence for the new lot.
For example, a fictional repeat order might show a matching product code but a certificate for a different lot. Mark the lot match as unresolved and request the correct record through the laboratory's normal purchasing process. Do not silently replace the lot number in your own file.
Use a documented acceptance decision
Have the responsible laboratory reviewer decide whether the supplied evidence meets the intended procurement specification. A purchasing checklist can flag gaps; it cannot infer unreported sterility, contaminant testing, or experimental suitability from a purity result.
Record acceptance, rejection, or a pending clarification with the reviewer and date. Keep any return or replacement terms alongside the decision so unresolved paperwork does not become an untracked cost. Reuse the checklist for each received lot, including repeat purchases; it contains no recommendation to buy a particular supplier.
Check the underlying evidence
Sources & review dates
- Bachem quality control: identity, purity, and content ↗Accessed 2026-09-14
Sources are documentary evidence. They do not establish firsthand testing of a listed supplier.