Before you buy research peptides, understanding the Certificate of Analysis (COA) is crucial. This document is your proof of a peptide’s quality and identity. Here’s how to read the key sections.
What is a COA?
A Certificate of Analysis is a lab-generated report for a specific batch (“lot”) of a product. A reputable vendor will provide a batch-specific COA, meaning the lot number on your vial matches the one on the document.
Key Sections to Decode:
- Product & Batch Info
What it is: Basic identifying details.
What to look for: Confirm the Product Name and, most importantly, the Batch/Lot Number match your vial exactly. This proves the results are for your specific sample.
- Purity (The Most Important Metric)
What it is: The percentage of the correct peptide versus impurities.
How it’s measured: By HPLC (High-Performance Liquid Chromatography).
What to look for: A purity of ≥ 98% is the research gold standard. Look for the attached chromatogram—a single, sharp peak is ideal; multiple small peaks indicate impurities.
- Identity Confirmation
What it is: Proof that the amino acid sequence is correct.
How it’s measured: Mass Spectrometry (MS) is most common. It shows the “Found Mass” should be nearly identical to the “Theoretical Mass.”
What to look for: Confirmation that the mass is correct. This is your evidence you have the right molecule.
- Peptide Content
What it is: The actual amount of pure peptide in the vial. The powder weight includes water and counterions from purification.
What to look for: A “Peptide Content” percentage (e.g., 89.2%). This is normal and expected.
Red Flags: When to Be Cautious
- No Batch-Specific COA: If a vendor can’t provide a COA for your exact lot, do not buy.
- Generic COA: A “representative” COA not tied to a lot number is useless.
- Low Purity: Be wary of purity consistently below 95%.
- Missing Mass Spec: A COA with only purity data and no identity confirmation is incomplete.
- No Third-Party Testing: The most trustworthy COAs come from independent labs, not the vendor themselves.
The Bottom Line
Always ask for the batch-specific COA before purchasing. A transparent vendor will gladly provide it. This simple step is the best way to ensure you get a quality product for your research