When purchasing a research peptide, the Certificate of Analysis (COA) is often the only independent evidence available about what is actually inside the vial. Understanding what a COA is, who produces it, and what its fields mean is a foundational skill for anyone evaluating peptide vendors — whether you are a researcher, a lab purchasing manager, or simply a curious reader trying to make sense of vendor documentation.
What a COA Is and Who Issues It
A Certificate of Analysis is a quality-control document that reports the results of analytical testing performed on a specific batch of a chemical or pharmaceutical compound. It confirms whether that batch meets pre-defined specification limits for identity, purity, and other relevant attributes.
COAs are issued by testing laboratories — either:
- In-house labs operated by the manufacturer or vendor themselves, or
- Independent third-party labs with no commercial stake in the product.
The distinction matters considerably. An in-house COA is produced by the entity selling the product. An independent third-party COA is produced by a laboratory that has no financial relationship with the vendor beyond the testing fee. Third-party labs such as Janoshik Analytical or Finnrick are commonly cited in the research peptide community as sources of independent batch testing. Pharmaceutical-grade manufacturers such as Bachem or PolyPeptide Group publish COAs produced under certified quality systems (ISO 17025, GMP).
What Fields a COA Typically Contains
A well-formed COA will include most or all of the following fields:
| Field | What It Reports |
|---|---|
| Product name / compound | The peptide or chemical being tested |
| Batch / lot number | Ties the certificate to a specific production run |
| Test date / expiry | When testing was conducted; some labs include a re-test date |
| Appearance | Visual inspection result (e.g., white lyophilized powder) |
| Purity (HPLC) | Percentage purity by High-Performance Liquid Chromatography — the core figure most buyers look at |
| Identity (MS / sequence confirmation) | Mass spectrometry confirmation that the compound is what it claims to be |
| Water content (Karl Fischer) | Residual moisture, relevant for accurate dosing in research contexts |
| Residual solvents | Checks for manufacturing solvent carry-over |
| Microbial / endotoxin | Sterility-relevant tests; not always present on peptides sold for research use |
| Pass / Fail notation | Whether the batch meets the lab's or manufacturer's specification |
The purity figure is the number most commonly cited in vendor listings. Research-grade peptides are commonly described in the literature and vendor documentation as targeting purity thresholds of 95% or higher by HPLC, though exact specifications vary by compound and intended use.
How to Tell a Real COA from a Vendor Screenshot
Not all documents labeled "COA" carry equal evidential weight. The following markers help distinguish credible certificates from superficial claims:
Indicators of a credible COA: - Identifiable issuing lab with a verifiable name, address, and accreditation number (ISO 17025 is the relevant standard for testing laboratories) - Batch/lot number that matches what appears on the product label - Raw chromatogram or spectral data attached or available on request — not just a summary percentage - Date of testing that is recent relative to the product's claimed shelf life - Contact information for the lab, allowing independent verification
Red flags: - A COA that shows only the vendor's own logo with no named testing laboratory - Purity figures with no associated methodology (e.g., no mention of HPLC) - No lot number, or a lot number that cannot be cross-referenced with the vendor's order records - A static image or PDF that cannot be verified against a lab portal — some independent labs (Janoshik, Finnrick) publish results publicly by lot number, which allows independent lookup
Platforms such as Finnrick.com and Peptigrity publish batch-level test results that consumers can search by vendor and compound. These aggregated records allow comparison across vendors for the same peptide, providing a broader picture than any single COA.
A COA is a starting point for quality evaluation, not a guarantee. How a lab is accredited, how samples are submitted (vendor-submitted versus blind third-party purchased), and how frequently a vendor tests its inventory all affect the informational value of any given document.
Sources
- Finnrick — independent peptide testing results
- Janoshik Analytical — independent peptide and chemical testing
- Peptigrity — vendor and batch quality aggregator
- Bachem — pharmaceutical peptide COA documentation
- USP (United States Pharmacopeia) — compendial quality standards
- FDA — guidance on certificates of analysis for drug products