Certificates and labels
Documentation is the only part of a purity claim you can check yourself. Here is how to read it.
- What is a Certificate of Analysis?
- How do you read a Certificate of Analysis?
- Should every peptide lot come with a certificate?
- What is a lot number?
- Why do lot numbers matter?
- What is a CAS number?
- What does a CAS number tell you?
- How do you read a peptide vial label?
- How do you document peptide research properly?
What is a Certificate of Analysis?
A Certificate of Analysis is the test record for one specific batch. It states what was tested, by which laboratory, on what date, and what the results were. It is batch-specific by definition — a certificate that is not tied to a lot number describes no particular material.
Full guide: How to Read a Peptide Certificate of Analysis (CoA) →
How do you read a Certificate of Analysis?
Check five things: the lot number matches your vial, the testing laboratory is named and independent, an HPLC purity figure is reported, mass spectrometry confirms identity, and the test date is present and recent. If the lot number does not match your label, the rest of the document is about someone else's material.
Full guide: How to Read a Peptide Certificate of Analysis (CoA) →
Should every peptide lot come with a certificate?
Yes — a certificate describes one batch, so a new batch needs a new certificate. A supplier reusing one certificate across multiple lots is showing you a document that no longer describes what is in your vial. Lot-specific documentation is the baseline, not a premium feature.
Full guide: How to Read a Peptide Certificate of Analysis (CoA) →
What is a lot number?
A lot number identifies one production batch. It is the key that ties a physical vial to its test data: the number printed on the label should appear on the certificate. Without it there is no way to prove a given certificate describes the material actually in your hand.
Why do lot numbers matter?
Because they make traceability possible. If a result looks anomalous, the lot number lets you check whether other work used the same batch. If a batch is ever withdrawn, it identifies exactly which material is affected. Without lot numbers, every quality question becomes unanswerable.
What is a CAS number?
A CAS Registry Number is a unique identifier assigned by the Chemical Abstracts Service to a specific chemical substance. It removes naming ambiguity — one compound can have many names and spellings, but only one CAS number, which makes it reliable for looking up literature.
What does a CAS number tell you?
It tells you exactly which substance is meant, and nothing else. A CAS number confirms identity of the compound in the abstract; it says nothing about the purity, quality or handling of the material in a particular vial. It is a naming tool, not a quality indicator.
How do you read a peptide vial label?
A label should carry the compound name, the quantity in milligrams, the lot number, and a research-use statement. The lot number is the one to check first, because it is what connects the vial to its certificate. Quantity refers to the peptide itself, not the total mass of powder in the vial.
How do you document peptide research properly?
Record the lot number alongside every result, not just the compound name. Note reconstitution date, diluent used, concentration, and storage conditions. If a result later looks anomalous, those details are what let you tell an experimental effect from a material or handling variable.