How to read a peptide lab report (COA)

A certificate of analysis is a lab's record of what it measured in a sample. For peptides, a useful one answers four questions:

1. Is it the right molecule? (identity)
2. How much of the peptide material is the target peptide? (purity)
3. How much peptide is in the vial compared with the label? (content)
4. Is it free of contamination that matters for injection? (endotoxin, sometimes sterility)

Most COAs you see online answer only the first two. That still leaves you guessing on dose and safety.

A COA is only evidence about the sample that was tested. Check:

• A lot or batch number that matches the one on your vial.
• A test date, and a sample description (compound, labeled amount).
• The name of the testing lab and a way to verify the report with them.
• The method used for each result.

A report with no lot number, or the same report for every batch, does not tell you anything about your vial.

Mass spectrometry measures the mass of the molecules in the sample. The report should show the expected molecular weight of the peptide and the mass observed. They should match within the method's tolerance.

Identity is the check that catches a vial that is clean but simply the wrong peptide. HPLC alone cannot do that.

HPLC separates the sample into peaks. Purity is the target peak's area as a share of all the peaks, usually read with UV light at 214 nm for peptides.

What purity means: of the peptide material detected, how much is the peptide you wanted rather than broken or incomplete versions.

What purity does not mean: it does not count water, salts or counterions such as TFA, so it is not the share of the powder's weight that is peptide. It says nothing about sterility or endotoxin. Look for the actual chromatogram, not just a number. One tall main peak with small side peaks is what a clean result looks like.

This is the number that changes your dose. Peptide powder always contains some water, salts and counterions, so the amount of actual peptide is less than the gross weight. Labs report it as net peptide content, or as a measured amount per vial.

If a report says a 10 mg vial contained 8 mg, your real doses are about 20% lower than your math assumes. If a report gives only purity, you do not know the content.

Some people use a measured content to adjust their mixing math. Our calculators let you enter your vial's real amount instead of the label figure.

Endotoxins are pieces of bacterial cell walls. They are not removed by killing bacteria and can cause fever, chills and flu-like reactions when injected. The standard test (LAL) uses an extract from horseshoe crab blood cells; FDA guidance covers how drug makers run it.

FDA has warned compounders after reports of severe chills, shaking and vomiting following NAD+ injections made with an ingredient not suited to sterile use, symptoms consistent with endotoxin.

If a COA has no endotoxin line, it was not tested. Sterility testing is a separate test again and is rare on research peptide reports.

• No lot number, or a lot number that does not match the vial.
• A purity figure with no chromatogram, or a chromatogram with no scale or labels.
• No identity test.
• No lab name or no way to verify the report with the lab.
• The same report reused across different batches or sizes.
• Content never reported, only purity.

None of these prove a product is bad. They mean the report is not doing its job.

A clean report covers one sample at one point in time. It cannot tell you how your vial was stored and shipped afterward, whether it is the same batch you received, or whether a compound works. Research peptides are labeled for research use only, and nothing on a COA turns them into a tested medicine.