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Leave siteA certificate of analysis looks like it was written for chemists. It was. But you don't need a lab coat to read one — you need to know where to look. This guide walks you through it in plain English, one box at a time.
⏱ 5-minute readNo chemistry degree required
In a hurry?
If you only check three things, check these.
A COA covers one batch only. The lot on the certificate should be the lot printed on your vial.
That's the HPLC number. It tells you how much of the vial is the peptide and how much is everything else.
Mass spectrometry confirms it's the right molecule — the measured mass should line up with the expected one.
What a COA actually is
A certificate of analysis is issued by a testing lab after it runs tests on a sample from one production lot. For research peptides, it answers three questions: Is it what the label says? (identity) How much of it is that compound? (purity) Is anything unwanted in it? (contaminants such as endotoxin).
Here's what a typical one looks like, and what each part means.
The lab's name and a way to reach it. Independent third-party labs beat in-house testing.
Compound, size and lot number. Match the lot to your vial.
When the sample arrived and when the results were reported.
The graph behind the purity number. One tall peak is what you want to see.
Proof by mass spectrometry that the molecule is the right one.
A pass/fail result against a stated limit.
Test 1 · Purity
High-performance liquid chromatography (HPLC) pushes a sample through a column so each ingredient comes out at a slightly different time. A detector records each one as a peak on a graph called a chromatogram.
Your peptide should be the one tall, sharp peak. The little bumps are everything else — shortened sequences, leftovers from synthesis. Purity is simply the main peak's area as a share of all the peaks combined.
main peak÷all peaks=purity %
Most of the market treats 98% as acceptable. HAUZ Research requires 99% or higher on every lot.
Test 2 · Identity
Here's the catch with purity: a vial can be 99% pure of the wrong thing. That's why identity matters. Mass spectrometry (MS, often LC-MS) weighs the molecules and checks the result against what that peptide should weigh.
Peptides usually pick up extra charges in the instrument, so the result is shown as a mass-to-charge ratio (m/z) with a label like [M+2H]2+. Don't let that throw you. The only question is: does the measured number match the expected one?
Worked example · BPC-157
It matches. Identity confirmed.
Test 3 · Endotoxin
Endotoxins are fragments of bacterial cell walls. Even tiny amounts can throw off lab work, especially cell-based experiments. They're measured with the LAL assay and reported in endotoxin units (EU) per mL or per mg. Look for a clear pass against a stated limit.
What you want to see: Pass, below the stated limit.
Often confused
They answer different questions. A 10 mg vial can be 99% pure and hold slightly more or less than 10 mg. Some COAs report both.
Trust, but verify
Most certificates are genuine. These are the signs one might not be.
Tip: When in doubt, contact the lab directly with the report number. Many labs offer an online verification code.
How we do it
Each lot is independently tested before it's sold, and every certificate is published in our COA Library — searchable by compound or lot number. Product pages link straight to the certificate for the size you're viewing.
Search the COA Library →It’s the share of the material detected by HPLC that is the target peptide, worked out from the area of the main peak compared with all peaks combined.
98% or higher is a common expectation for research peptides. HAUZ Research requires 99% or higher for every lot.
A COA describes one production lot only. If the lot on the certificate doesn’t match the lot on your vial, the results don’t apply to what you have.
It means the molecule picked up two extra protons in the instrument, so it is read at half its mass. The key check is that the measured value matches the expected value for that peptide.
Purity is the share of the material that is the target peptide. Net content is how many milligrams of peptide were measured in the vial.
Search the COA Library by compound name or by the lot number printed on your vial.
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