Ventra LabsWhat is on a certificate of analysis?
How to read a certificate of analysis
What a certificate of analysis states, what HPLC and mass spectrometry each establish, and what a purity figure does and does not tell you.
What the document is
A certificate of analysis is the laboratory's own statement of what it found when it tested a sample. It is issued to whoever commissioned the test — for material made under contract, that is the manufacturer rather than the seller, which is why a manufacturer's name usually appears on the document and a seller's does not.
It is a record of one sample from one batch on one date. It is not a description of a product line, and a certificate for a batch made in March says nothing about a batch made in September.
Purity, by HPLC
High-performance liquid chromatography separates what is in the sample and measures how much of the total each part accounts for. The purity figure is the proportion of the material that is the intended compound, usually expressed as a percentage of the area under the chromatogram.
A figure of 99% means one per cent of what was measured was something else. It does not identify what that something else is, and it is a proportion of what the method detected — a substance the method does not detect is not in the denominator. Purity by HPLC is a strong statement about composition and a weak one about everything the method cannot see.
Identity, by mass spectrometry
Mass spectrometry measures molecular mass, which is how a laboratory establishes that the material is the compound it is said to be rather than a different one of similar appearance. A certificate states the mass found and the mass expected for that compound.
The two tests answer different questions and neither substitutes for the other. Purity without identity says the sample is 99% one thing without saying which thing. Identity without purity says the right compound is present without saying what else is.
What to check on the document itself
The laboratory should be named, and the certificate should carry a reference under which that laboratory files its own copy. Without both, the document cannot be checked against anything and is a claim rather than a record.
The date of analysis should be present, and the batch number on the certificate should be the batch number printed on the box in front of you. A certificate that does not name a batch cannot be matched to the material it is supposed to describe.
How this site publishes them
Each batch has its own page, reached with the number printed on the box. That page shows the figures in our own type and links the laboratory's document unaltered, with the reference needed to check it with the laboratory directly.
Where a batch has been made but its result has not been issued, the page says so and shows nothing else — no figure from an earlier batch, no average, and no manufacturer expectation.
Holding a vial? Look it up on the batch page. What is recorded for every batch is set out under quality and documentation.