Certificate of Analysis: What It Can and Cannot Tell You
A high-level overview of certificates of analysis (COAs) for peptide products — what they test, their limitations, and common red flags.
Filed under safety quality, written for beginner, patient-consumer, pharmacist-compounder, researcher, evidence level risk-flag.
Not medically reviewed. Last updated 2026-03-25. Nothing here is medical advice.
A Certificate of Analysis (COA) is a document that reports the results of quality testing performed on a specific batch of a product. In the peptide space, COAs are often cited as evidence of product quality, but understanding their limitations is important.
What a COA Typically Includes
**Identity confirmation**: Usually via mass spectrometry (LC-MS or MALDI)
**Purity assessment**: Typically via HPLC (High-Performance Liquid Chromatography)
**Appearance**: Physical description of the product
**Water content**: Via Karl Fischer titration
**Peptide content**: Net peptide weight
**Batch/lot number**: Links the COA to a specific production batch
What a COA Cannot Tell You
**Sterility**: Standard COAs rarely include sterility testing. For injectable products, sterility is critical.
**Endotoxin levels**: Bacterial endotoxin testing (LAL) is essential for injectables but often omitted.
**Long-term stability**: A COA reflects a snapshot at testing time.
**Manufacturing conditions**: A COA does not certify GMP manufacturing.
**Regulatory compliance**: A COA does not mean the product is legal to sell or use.
Common Red Flags
COA from the manufacturer only (no third-party verification)
Missing lot/batch numbers
Purity claims above 99.9% (suspiciously high)
No date on the analysis
Generic templates reused across products
No contact information for the testing laboratory
Important Context
A COA is one data point, not a guarantee of safety or quality. It is not a substitute for pharmaceutical-grade manufacturing, regulatory approval, or medical supervision.
This guide is for educational purposes and does not evaluate specific products or laboratories.