A certificate of analysis is the single most useful document in the research peptide market, and the one most often waved around without being understood. Vendors advertise "99% purity" on every page. The COA is where that number either holds up or falls apart. This guide explains what each section of the document actually tells you, and which parts are worth more than others.
What a COA is
A certificate of analysis is a laboratory report on one specific batch of material. That last part matters more than anything else on the page. A COA is not a certificate for a product line, a brand, or a supplier. It applies to one batch, identified by a batch or lot number, tested on a particular date.
This is why "we test our peptides" is a weaker claim than it sounds. The question is whether the vial in front of you belongs to the batch that was tested.
The sections that matter
Product identity and batch number. The compound name and the batch or lot number should both appear. The batch number is what lets you connect the document to the vial. If a COA has no batch number, it cannot be tied to anything.
Test date. A COA describes the material at the moment it was tested. A report from three years ago tells you less than one from three months ago.
Purity by HPLC. High-performance liquid chromatography separates the components of a sample and measures how much of each is present. The purity figure is the percentage of the sample that is the intended compound. This is the headline number, and it should be supported by a chromatogram — a graph showing peaks. The main peak should dominate; small side peaks are impurities.
Mass spectrometry. HPLC tells you how much of the sample is one substance. Mass spectrometry tells you whether that substance is the right one. It measures molecular weight, which should match the theoretical weight of the peptide within a narrow tolerance. A sample can be 99% pure and still be 99% pure something else — MS is the check against that.
Appearance and physical description. Usually a short line: white to off-white lyophilized powder. Simple, but if the material in the vial does not match the description, that is a real signal.
Testing laboratory. Who ran the analysis. Third-party testing carries more weight than in-house testing for an obvious reason: an independent laboratory has no commercial stake in the result.
Reading the chromatogram
You do not need to be an analytical chemist to get value from the graph. Look for one tall, sharp, dominant peak. Multiple peaks of comparable height mean the sample contains multiple substances in meaningful quantities. A broad, low, poorly defined main peak suggests degradation or a poorly resolved separation.
Warning signs
No batch number. A COA that cannot be tied to a specific lot is decoration.
Only a summary. A table stating "Purity: 99%" with no chromatogram is a claim, not evidence. The graph is the data; the number is the interpretation.
No mass spectrometry. Purity without identity is half the picture.
In-house testing only. Not automatically disqualifying, but it means the party selling the material also graded it.
COA "available on request". If a document exists and is favourable, there is no reason to make a buyer ask for it. Publishing it is easy. Withholding it is a choice.
Why we publish ours
Every HolyPeps compound is third-party lab tested and the certificate of analysis is published directly on the product page. Not on request. Not summarized into a number. The document itself, there to read before you decide.
That is the whole differentiator, and it is deliberately the easiest thing about us to verify. Open any product page and look for yourself — GHK-Cu, BPC-157, or anything else in the catalog.
Research use only. These compounds are supplied for laboratory and research purposes and are not intended for human or veterinary use.