A certificate of analysis is the manufacturer's test record for a specific production lot. Suppliers hand them out freely, and most buyers glance at the purity figure and stop. The rest of the document is where the useful information sits.
First: does it match your vial?
Before reading anything else, compare the lot number on the certificate against the lot number printed on your vial. If they differ, the document tells you nothing about what you are holding.
A generic certificate circulated to every customer is marketing, not verification. This is the single most common way COAs are used to create false confidence.
HPLC purity
High-performance liquid chromatography separates the sample into components and measures the proportion of each. The headline purity figure — typically 98% or higher for research peptides — represents the target peptide as a percentage of total peptide content.
The chromatogram itself is worth examining if included. A clean trace shows one dominant peak. Multiple significant peaks indicate impurities or degradation products, regardless of what the summary figure says.
Note what purity does not tell you: it is a proportion, not an identity check. A sample can be 99% pure and still be the wrong compound.
Mass spectrometry
This is the identity check. Mass spec measures the molecular weight of the compound and compares it against the theoretical weight calculated from the amino acid sequence.
The observed and theoretical values should match closely. A discrepancy means the sequence is not what the label claims — a missing or substituted amino acid changes the mass in a detectable way.
Purity plus mass spec together answer both questions: is it the right compound, and how much of the sample is that compound.
Water content and peptide content
Lyophilised peptides absorb moisture. Water content, often measured by Karl Fischer titration, is typically a few percent.
Peptide content matters more than most buyers realise: it reports how much of the vial's total mass is actual peptide, with the remainder being water, counterions such as acetate or trifluoroacetate, and residual solvents. A vial labelled 10 mg with 80% peptide content contains approximately 8 mg of peptide. Suppliers rarely volunteer this distinction.
Appearance, date and testing body
Check the test date — a certificate dated years before your vial was produced is not describing your lot. Note whether testing was performed in-house by the manufacturer or by an independent laboratory. Independent testing carries more weight, though in-house testing from a reputable manufacturer is normal practice.
Quick checklist
- Lot number matches your vial
- HPLC purity stated, ideally with the chromatogram
- Mass spec: observed weight matches theoretical
- Peptide content stated, not just gross mass
- Test date is consistent with the production lot
- Testing body identified
Quote the lot number printed on your Space Pep vial and we will supply the manufacturer's certificate for that lot. See also how to verify peptide authenticity.
All products supplied by Space Pep are intended strictly for laboratory research purposes. They are not drugs, foods, cosmetics, or medical devices, and are not intended to diagnose, treat, cure, or prevent any disease.