How to Read a Peptide COA: A Plain Guide to Certificates of Analysis

A certificate of analysis (COA) is the record of what a laboratory found when it tested a specific batch. For research peptides it is the single most useful document a supplier can give you, as long as you know what to look for.

What a COA should tell you.

A useful peptide COA answers four questions:

1. Which batch? A lot number that matches the label on your vial or bottle.
2. What is it? Identity: evidence the material is the compound named.
3. How pure is it? A purity figure, usually from HPLC.
4. Who tested it, and when? The testing laboratory and the date.

Reading HPLC purity.

High-performance liquid chromatography (HPLC) separates the components of a sample as it flows through a column. A detector records each component as a peak on a chart called a chromatogram.

• The main peak is the target peptide. It appears at a characteristic time, called the retention time.
• Smaller peaks are impurities, such as shorter or altered peptide chains left over from synthesis.
• Purity is the area of the main peak as a share of the total area of all peaks. A result of 99% means the main peak accounts for 99% of what the detector saw.

A chromatogram that shows one tall, sharp peak and little else is what you hope to see.

Identity testing.

Purity tells you how much of the sample is one compound. Identity tells you which compound it is. Certificates confirm identity in one of two common ways:

• Retention time against a reference standard. The sample and a certified reference standard of the compound run through the same HPLC method. If the main peak appears at the same time as the standard, identity is confirmed. Certificates often cite USP <621>, the standard method for chromatography.
• Mass spectrometry (MS). MS measures the molecular mass directly and compares it with the expected value.

Either way, the certificate should state how identity was confirmed.

Matching the lot.

A COA only tells you about your material if the lot number on it matches the lot number on your label. Always check the product name, the stated amount and the lot number against what you received.

What deserves a closer look.

• No lot number, or a lot number that doesn’t match your label.
• No chromatogram, just a number.
• Purity stated as exactly 100%, which real chromatography almost never shows.
• The same certificate reused across different products or strengths.
• No date or no named testing laboratory.

Our certificates.

Every Success Bio Labs lot is third-party HPLC tested for identity and purity. Certificates in our COA library are organised by product and strength. Select your product, then check the product name, strength and lot number on your label against the report.

Some product pages, such as tesamorelin and PT-141, list a labeled purity of more than 99%. The certificate is the record behind that figure.

Where to go next.

Once your material checks out, see how to reconstitute peptides. To browse the catalogue, start with peptide vials, capsules or liquid sprays.

Questions.

What does COA stand for?

Certificate of analysis: a laboratory’s record of test results for a specific batch.

What is a good HPLC purity for a research peptide?

Research suppliers commonly quote 98% or 99% and above. More important than the headline number is a chromatogram and a lot number that matches your material.

What is retention time?

The time the target compound takes to pass through the HPLC column. It helps identify the main peak.

Where are your certificates?

In our COA library, organised by product and strength. Check your label against the report.

For laboratory research use only. Not for human or veterinary use. Nothing in this article is medical advice or guidance on human use.