Testing & Quality
How to Read a Peptide Certificate of Analysis (COA)
Healthy Aminos Research Team · · 6 min read
Why COAs Matter
A Certificate of Analysis (COA) is a document issued by an analytical laboratory that reports the results of testing performed on a specific batch of material. For research-grade peptides, the COA provides objective evidence of identity, purity, and quality.
Key Sections of a Peptide COA
Identity (HPLC)
This section confirms that the compound is what it claims to be. The HPLC retention time of the sample is compared against a reference standard. A match within an acceptable window (typically ±0.5 minutes) confirms identity.
Purity (HPLC)
Purity is expressed as the percentage of the total chromatographic area corresponding to the target peptide peak. Research-grade peptides typically range from 95-99%+ purity. Higher purity means fewer synthesis-related impurities.
Mass Spectrometry (MS)
Mass spectrometry confirms the molecular weight of the compound. The observed mass should match the theoretical molecular weight within the instrument's accuracy (typically ±1 Da for ESI-MS). This provides orthogonal confirmation of identity beyond HPLC retention time.
Endotoxin Testing
Endotoxins are lipopolysaccharide components of gram-negative bacterial cell walls. They can interfere with biological assays. The Limulus Amebocyte Lysate (LAL) assay is the standard method. Results should be below the specified threshold (typically <0.5 EU/mg).
Sterility Testing
Confirms the absence of viable microorganisms. Important for any compound used in cell culture or sensitive research applications.
Peptide Content
Reports the actual peptide mass as a percentage of the total vial weight (which includes counter-ions, moisture, and residual solvents). Typical values range from 60-85%. This is NOT the same as purity — a 98% pure peptide might have 75% peptide content.
Red Flags
- Missing batch number (a COA should be traceable to a specific batch)
- No laboratory name or accreditation information
- Purity reported without a chromatogram image
- Mass spec data showing multiple peaks of similar intensity
- No date of analysis
Research Use Only
FOR RESEARCH USE ONLY. Products sold by Healthy Aminos are intended strictly for in-vitro research and laboratory use. Not for human or animal consumption. Not FDA approved. By purchasing from Healthy Aminos, the buyer acknowledges that these products are not intended to diagnose, treat, cure, or prevent any disease. All products are sold as reference standards and research chemicals only.