How to Read a Certificate of Analysis

What a Certificate of Analysis is

A Certificate of Analysis (COA) is an independent laboratory's written record of what was actually measured in one specific production batch of a reagent — not a general spec sheet for the product line. Every batch DexaLabs sells gets its own COA, generated after a third-party lab receives a sample and runs its own tests. If a document doesn't reference a specific batch or lot, it isn't telling you anything about the vial in front of you.

Purity by HPLC

High-Pressure Liquid Chromatography (HPLC) separates a sample into its individual components and reports each one as a percentage of the total peak area. The purity figure on a DexaLabs COA — target ≥99% — is the area-percent belonging to the single main peak. A trustworthy COA includes the chromatogram image itself, not just the number: a single sharp, well-resolved peak with minimal shoulder or baseline noise is what supports a high purity figure. A purity percentage with no chromatogram attached is a number you have no way to check.

Identity by mass spectrometry

Purity tells you how much of the sample is one substance; mass spectrometry (MS) tells you which substance it is. The lab compares the observed mass of the sample to the expected (theoretical) mass calculated from the peptide's known molecular formula. A close match, usually within a small tolerance window, confirms molecular identity — that the vial actually contains the peptide named on the label, not merely something pure.

Appearance and water content

The physical description on a COA — typically "white to off-white lyophilized powder" or "cake" — should match what you see when you open the vial. Water content, often measured by the Karl Fischer method and reported as a percentage, matters because a lyophilized reagent with too much residual moisture is more prone to degrade over time in storage.

Endotoxin, when listed

Some certificates include an endotoxin figure, reported in EU (endotoxin units) per milligram. This measures bacterial contamination carried over from the manufacturing process and is reported more consistently on some product lines than others. Its absence on a given COA isn't automatically a red flag — check the product's quality page for what's tested on that line — but when it is reported, it should read as a specific number, not a vague pass/fail label.

Lot/batch number, test date, and the testing lab

Three fields tie a COA to reality: the batch or lot number, the date testing took place, and the name of the independent laboratory that did the work. The lab should be a real, named, contactable organization — not just "third-party lab" with no identifying detail. DexaLabs publishes the lab name alongside every COA on /quality and on the relevant product page.

Matching a certificate to your vial

Before relying on any figure on a COA, check that the batch or lot number printed on the certificate matches the one printed on your vial's label. A certificate for a different batch of the same product tells you nothing about the vial you're holding, even when the product name is identical.

Signs of a fabricated certificate

• No batch or lot number anywhere on the document.
• No named laboratory, or a lab name that returns nothing when you search for it.
• A purity number with no chromatogram, spectrum, or other supporting data behind it.
• Numbers, fonts, or layouts that look copy-pasted across certificates for different products.
• No test date, or a test date that predates when the product itself became available.
• A document you can't find published on DexaLabs' own quality page or the relevant product page, when one is claimed to exist there.