How to Read a Certificate of Analysis for Research Peptides
A Certificate of Analysis (COA) is the primary document verifying that a research compound meets stated quality specifications. Every product we ship comes with a third-party COA. Here is how to interpret one.
What is a COA?
A Certificate of Analysis (COA) is a quality assurance document issued by a testing laboratory that confirms a specific batch of a compound meets defined purity and identity specifications. For research peptides, a COA typically documents the results of HPLC purity analysis and sometimes additional tests such as water content or microbial limits. It is tied to a specific batch or lot number and is non-transferable between batches.
Key sections of a peptide COA
Product name and batch/lot number
Always verify the product name and batch number on the COA matches the label on your vial. Batch numbers are critical — a COA for a previous batch does not apply to a new shipment.
HPLC purity (%)
High-Performance Liquid Chromatography (HPLC) measures the purity of the compound by separating it from impurities on a column. A result of ≥98% means at least 98% of the detected substance is the target peptide. At ACCUTIDE, all products carry a minimum ≥98% HPLC purity, with most at ≥99%.
Water content (Karl Fischer)
Lyophilized peptides can absorb moisture. The Karl Fischer test measures residual water content. A lower water content (typically <5–8%) indicates better lyophilization and longer shelf stability.
Testing laboratory name and accreditation
A credible COA is issued by an independent, accredited third-party laboratory — not the supplier's own in-house team. Look for ISO/IEC 17025 accreditation or equivalent. The lab name, address, and analyst signature should appear on the document.
Red flags to watch for
- COA issued by the same company selling the product (not third-party)
- Missing batch or lot number
- Purity reported without specifying the test method (HPLC, etc.)
- COA date significantly older than the product shipment date
- Purity below 95% for a research-grade compound
COA requests at ACCUTIDE
All ACCUTIDE Research Supply products ship with third-party COA documentation. You can also request COA documentation for any specific batch via our COA request page or by contacting us directly.
Related guides: What is RUO? · Why batch testing matters