Research Notice: All peptides sold by The Peptide Store are intended for laboratory research purposes only. They are not for human consumption, not approved by the FDA, and not intended to diagnose, treat, cure, or prevent any disease.
Research summary: Evaluating research-peptide quality centers on the Certificate of Analysis (COA) — a batch document reporting identity confirmation, purity percentage, and molecular-weight confirmation. HPLC (High-Performance Liquid Chromatography) is the standard purity test, and research-grade peptides should show ≥98% purity by HPLC. Suppliers unable to provide batch-specific HPLC data should be treated with caution. Sold for laboratory research use only.
For researchers working with peptides, the quality and purity of sourced compounds is foundational to valid results. Understanding how to evaluate peptide quality documentation is essential knowledge for responsible research sourcing.
What Is a Certificate of Analysis?
A Certificate of Analysis (COA) is a document issued by an analytical laboratory reporting test results for a specific batch of compound. For research peptides, a proper COA should report: peptide identity confirmation, purity percentage, molecular weight confirmation, and often water and acetate content for lyophilized materials.
HPLC: The Primary Purity Test
High-Performance Liquid Chromatography is the standard method for assessing peptide purity. HPLC separates compounds by chemical properties and measures the relative abundance of the target compound versus impurities. Research-grade peptides should show ≥98% purity by HPLC. Vendors unable to provide HPLC data should be viewed with significant skepticism.
Mass Spectrometry: Identity Confirmation
Mass spectrometry confirms compound identity by measuring the mass-to-charge ratio and comparing it to the theoretical molecular weight. An MS result confirming the expected molecular weight verifies you have the correct compound, not an impurity or substitution.
Third-Party vs. In-House Testing
The most credible COAs come from independent third-party laboratories with no financial interest in the results. In-house testing by the vendor is inherently less reliable than testing by an accredited external lab. All products at The Peptide Store are tested by independent analytical laboratories. Current batch COAs are available on our Lab Testing & COAs page.
Red Flags to Watch For
Be cautious of suppliers who cannot provide COAs on request, provide only in-house data, list purity without specifying the testing method, show COA dates inconsistent with current inventory, or whose documentation formatting appears unprofessional or inconsistent with standard analytical reports.