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How to read a research material's COA

In brief

A COA (Certificate of Analysis) is the document in which a laboratory records test results for a specific batch. Read it in four steps: who issued it, which batch it covers, which methods were used, and what exactly was measured. A COA with no batch linkage and no stated methods confirms almost nothing.

Illustration for the research article

Step 1. Who issued the document

The first check is the source: the manufacturer's own laboratory, an independent laboratory, or an unidentified author. These deserve different levels of trust, and an honest seller distinguishes them explicitly. The laboratory name, date, and report identifier should be present in the document, not implied.

Step 2. Which batch it covers

A COA only means something in connection with a specific batch (lot). If your vial is batch A and the document describes batch B, it confirms nothing about your material. A missing batch number is the most common and most serious documentation defect in the research-materials market.

Step 3. Which methods produced the results

Every figure should name its method: chromatography (HPLC) for purity, mass spectrometry for identity, gravimetric or amino-acid methods for quantity. A result without a method cannot be checked. Different methods answer different questions — a high HPLC purity percentage says nothing about how much substance is in the vial.

Step 4. What was measured — and what was not

Identity, purity, quantity, sterility, and endotoxins are five different properties. A certificate covering one does not cover the rest. This is the central principle behind the Moscow Peptides quality page: we state what is documented and never stretch one measurement to imply another.

References

  1. Electrospray Mass Spectrometry and Tandem Mass Spectrometry of Synthetic Multicomponent Peptide Mixtures: Determination of Composition and Purity — Analytical Biochemistry, 219(2), 261–277 (PMID 8080083; DOI 10.1006/abio.1994.1266), 1994.
  2. Reversed-Phase High-Performance Liquid Chromatography in Peptide and Protein Analysis — Encyclopedia of Analytical Chemistry (DOI 10.1002/9780470027318.a1631), 2000.