How to Read a COA

01 What Is a COA?

A Certificate of Analysis (COA) is a document issued by a laboratory – either the manufacturer’s in-house lab or an independent third-party lab – that reports the results of quality testing performed on a specific batch of product.

Every legitimate peptide vendor should provide a COA for every batch they sell. The COA is batch-specific, meaning the results apply only to the lot number printed on the document, not to the product in general.

A complete COA typically includes four core tests: HPLC purity analysis, mass spectrometry identity confirmation, endotoxin testing, and physical appearance assessment. Let’s break down each one.

02 HPLC Purity Testing

High-Performance Liquid Chromatography (HPLC) is the gold standard for measuring peptide purity. It separates the sample into individual components and measures what percentage of the total is the target peptide versus impurities.

03 Mass Spectrometry (MS)

While HPLC tells you how pure the sample is, mass spectrometry tells you what the sample actually is. It measures the molecular weight of the compound and compares it to the known molecular weight of the target peptide.

04 Endotoxin & Sterility Testing

Endotoxins are bacterial toxins that can cause fever, inflammation, and in severe cases, sepsis. The LAL (Limulus Amebocyte Lysate) test measures endotoxin levels in the sample.

05 Appearance & Solubility

These are basic physical tests that confirm the product looks and behaves as expected.

• ✓
  Appearance: Should read “white to off-white lyophilized powder” or similar. Discoloration, clumping, or liquid in a lyophilized product is a fail.
• ✓
  Solubility: Should dissolve clearly in bacteriostatic water or sterile water. “Clear, colorless solution” is the expected result. Cloudiness or particulates indicate contamination or degradation.
• ✓
  pH: If listed, should fall within the expected range for the specific peptide (typically 4.0 – 7.0 for most peptides in solution).

06 Red Flags – What to Watch For

Not all COAs are created equal. Here are the warning signs that a COA may be unreliable, fabricated, or misleading.

• ✗
  No lot/batch number. A COA without a batch number can’t be tied to a specific product. It could be recycled from a different batch or fabricated entirely.
• ✗
  No lab name or address. Legitimate labs put their name, address, and accreditation on every report. A COA with no lab identification is worthless.
• ✗
  Missing mass spec data. HPLC alone confirms purity but not identity. A vendor skipping MS is cutting the most important corner.
• ✗
  Purity always exactly 99.0%. Real lab results have decimal variation (98.73%, 99.14%). A round number on every batch suggests the results are templated, not tested.
• !
  In-house testing only. Not an automatic fail, but third-party verification is the standard. Ask if independent testing is available.
• !
  COA is an image, not a PDF. Some vendors post low-resolution screenshots of COAs that can’t be verified. Legitimate labs issue PDF reports. Ask for the original.
• !
  No date on the report. COAs should have an analysis date. Old COAs don’t reflect the current batch’s quality.
• !
  Generic chromatogram. If the HPLC graph looks identical across multiple products or batches, it may be a stock image rather than actual test data.

07 Your COA Checklist

Use this interactive checklist to evaluate any peptide COA. A trustworthy COA should check every box.