Reading a certificate of analysis

01 · What a CoA is, and what it is not

A certificate of analysis is a record of tests a laboratory says it performed on a specific batch of material. It is a report, not a guarantee, and not a licence. Nothing on it speaks to whether a compound does anything — that question belongs to the evidence grade and no certificate can move it.

What a good CoA establishes is narrower and more useful: that on a stated date, a named laboratory ran named methods on a batch bearing a stated lot number, and got these results.

Every field below is either checkable or decorative. Learning which is which is the whole skill.

02 · The fields, and what each one is asserting

Product name and sequence

Asserts what the supplier intended to make. It is not a measurement. A sequence printed on a certificate is transcription, and transcription is not analysis.

Lot or batch number

The single most important field. It is what ties this document to the vial in hand, and it is the field most often mismatched. Covered in full in explainer 04.

Test date

Must fall after the manufacturing date. An undated certificate is not a certificate. A certificate dated before the lot it describes is describing something else.

Purity, by HPLC

A percentage derived from a chromatogram. Meaningful only alongside the trace and the method. Covered in full in explainer 03.

Identity, by mass spectrometry

Confirms the measured mass matches the expected mass for the sequence. This is the field that answers “is it the right molecule”, and purity does not answer it. Covered in explainer 02.

Appearance, water content, endotoxin, residual solvents

Routine and genuinely useful, and routinely copied unchanged between lots. Identical values across several lots are a signal worth noticing.

03 · The three fields that cannot be faked without leaving evidence

1. The chromatogram image. A trace is a picture with a shape. Producing a convincing false one is real work, and reusing the same image across lots is visible the moment two are compared.
2. The lot number, cross-checked against the vial. Requires no expertise. Costs ten seconds.
3. The test date, cross-checked against the manufacturing date. An internally inconsistent document tells you about the process that produced it.

Everything else on a certificate can be typed by anyone. These three carry information about whether the work was done.

04 · What to do when a field is missing

A missing field is not proof of anything. It is an absence, and absences have boring explanations more often than sinister ones. The useful response is to ask, and to note whether the answer arrives as a document or as an assurance.

A supplier who publishes traces, states methods, and dates their certificates has made themselves checkable. That is a meaningfully different posture from one who publishes a number.

05 · What a CoA cannot tell you

It cannot tell you whether the compound has been studied in humans. It cannot tell you whether the proposed mechanism is established. It cannot tell you whether a regulator has approved anything.

Those are questions about the literature, and this publication answers them with an evidence grade that no supplier document can influence.