The one document that does the talking
Every research chemical is, in the end, a claim: this vial or strip contains a specific molecule, at a specific purity, in a specific amount. A certificate of analysis is the document that backs the claim with measurements. If you buy research peptides, learning to read one takes about ten minutes and will change how you evaluate every supplier, including us. Here is the anatomy of the document, section by section.
Identity: is it the right molecule?
The identity section answers the most basic question, usually with mass spectrometry. A mass spec result shows the measured molecular weight of the material; it should match the theoretical weight of the named compound. For a peptide like BPC-157 or Semax, some labs include the amino acid sequence confirmation as well. If a COA has no identity testing at all, the document is telling you the material was never actually confirmed to be what the label says.
Purity: how much of it is the right molecule?
Purity is normally measured by HPLC — high-performance liquid chromatography — which separates a sample into its components and reports each as a percentage of the total. The chromatogram itself, the graph with peaks, should be part of the document. The main peak is the target compound; the smaller peaks are synthesis leftovers, truncated sequences, and other related impurities. Research-grade material is generally expected to test at 98% purity or higher. A COA that prints a purity number without showing the chromatogram is asking you to take the number on faith.
Quantity and batch information
Three details connect the document to the physical product in your hand. The batch or lot number on the COA should match the number on the product label. The test date should be reasonably close to the batch's production, not years older. And the reported quantity should correspond to the labeled content — per strip, per bottle, or per vial. A mismatch on any of the three means the certificate describes some other batch than the one you received.
What else to look for
Serious certificates also cover some or all of the following: appearance and solubility observations, water content, residual solvent limits, heavy-metal screening, and — for material destined for cell work — bacterial endotoxin levels. The testing laboratory's name matters too. A COA issued by an independent third-party lab carries different weight than one a supplier produced in-house, and either is worth more than a generic template with no lab identified at all.
The five-minute check
Before ordering from any supplier, ask for the COA for the batch you would actually receive, then check: identity confirmed by mass spec, purity at 98% or above with the chromatogram shown, batch number matching the product, a recent test date, and a named laboratory. Suppliers who test properly can produce that document in one request. It is the fastest quality filter in this entire industry, and it works before you spend anything.
Continue reading: Best Sellers · Peptide Strips · Nasal Sprays