Guide · Verification

Four questions to ask before you trust a certificate of analysis

A certificate of analysis is one page of numbers, and it is usually read for about four seconds. These are the four things actually worth checking on it — in the order that matters.

Written by the peppies team · Information only, not medical advice

One
Does the batch on the certificate match what you received?

This sounds too obvious to check, and it is the single most common gap. A certificate covers one specific batch. If the batch reference on the page and the batch reference on the item in front of you are not the same string, the document describes something you don't have — no matter how good the numbers on it look.

Two
Which tests were actually run?

“Tested” is not one thing. Purity, identity and endotoxin are three separate tests on three separate instruments, and a certificate can report one while saying nothing at all about the others.

Purity by HPLC with UV detection tells you how cleanly the material separated. It does not confirm that the molecule is the molecule named on the label — that is an identity test, usually by mass spectrometry. Endotoxin is a third test again. Most single-page certificates show the first and are silent on the rest.

Three
Who commissioned it?

Whoever pays the laboratory chooses the laboratory, and chooses which sample goes into the envelope. That is not an accusation, it's just the structure. A certificate commissioned by a seller and a certificate commissioned by a buyer are different kinds of evidence, and it's worth knowing which one you're reading.

Four
Is the laboratory named?

An unnamed laboratory is an unverifiable claim. A named one can be looked up, and its methods and accreditation can be checked against what the certificate says it did.

What peppies does with this. Certificates are organised into two categories that are never mixed: supplier-submitted, and user-submitted from buyers and groups. In both cases the job is the same — check that the document corresponds to the batch and product it claims to describe, rather than assuming it does. The point isn't to catch anyone out. It's that a certificate nobody checks is decoration.

See how the check works

Create a free account to see how certificates are verified against the batch they claim to cover.

Free to join. No payment details needed. We use your address only for your account and the updates you asked for — how we handle your data.