How to read a certificate of analysis

What the document is for

A certificate of analysis is a batch record. A laboratory tested a specific lot of material and wrote down what it found. It describes that lot, on the day it was tested, by the methods it used.

It is not a license, an approval, or a safety review. Nobody outside the issuing organization has necessarily seen it.

The certificate does carry legal weight in one specific place. For a compounded medication to qualify for the exemptions in section 503A, two conditions apply to the bulk drug substance. It has to be made by a registered establishment, and it has to be accompanied by a valid certificate of analysis. That is a condition on a pharmacy, not a badge for a consumer.

The lines a certificate usually carries

Most certificates in this market are one page and cover a predictable set of fields.

Identity comes first: the substance name, a chemical registry number, the molecular formula and the molecular weight. Then appearance, usually a phrase like white to off-white lyophilized powder. Then purity, almost always by high performance liquid chromatography, reported as a percentage. Some add an amino acid analysis, a water content figure, or a mass spectrometry result confirming molecular weight.

That is a real set of measurements and it answers a real question: is this roughly the molecule it claims to be, and is most of what is in the container that molecule.

The lines that are usually missing, and why they are the ones that matter

A purity figure of 99 percent says nothing about the remaining one percent. For an injectable peptide, that remainder is the whole safety question.

Four measurements do that job and they are routinely absent. Impurity limits with testing results, which identify what the other material is rather than only how much of it there is. Aggregate testing, because peptide molecules that clump together are the form most likely to provoke an immune response. Microbial burden. Bacterial endotoxin, the fragment of bacterial cell wall that causes fever reactions and is not removed by sterile filtration.

FDA said this repeatedly across its July 2026 reviews. For BPC-157 it found that most certificates contain only purity results, with no information on impurity limits or testing to demonstrate control of the impurity profile. For MOTS-c it found a certificate containing only a purity result. For Semax it found one carrying identity, amino acid analysis and purity, and nothing else.

The agency drew the consequence rather than leaving it implied. Without impurity and aggregation data, it could not rule out the risk of an immune response to the injected product.

Sometimes there is no certificate at all

Two of the six substances reviewed in July 2026 had no certificate for one of their forms anywhere in the nomination package.

For KPV, there was no certificate for the free base form. For Epitalon, there was none for the free base either. For BPC-157, neither of the two nomination packages contained one for the free base. In each case the reviewers went looking in the published literature for one instead.

A nomination is a formal submission asking a federal agency to permit a substance in compounding. If the certificate is missing from that, the certificate on a retail product page is unlikely to be more rigorous.

The identity failure worth studying

The TB-500 nomination is the clearest example of a certificate failing at the one thing certificates exist to do.

FDA recorded four problems in a single package. The substance nominated was the free base, and the certificate supplied was for the acetate salt. The registry number, molecular formula and molecular weight on that certificate belonged to the acetate rather than to the free base. The molecular formula written in the nomination itself matched neither form. An alternate registry number in the package matched neither form.

The reviewers also noted that the molecular formula printed on the certificate was not legible.

FDA's conclusion was that the substance being nominated was unclear. A certificate had been supplied, so the box was ticked. It did not establish which molecule was in the container.

Free base and salt are not the same entry

The most common way a certificate misleads without lying is the free base and salt distinction.

Many peptides are sold either as a free base or as an acetate salt. Those are different active ingredients with different registry numbers, different molecular weights and, on paper, different quantities of active material per milligram.

FDA treats them as separate substances and evaluated each one separately in every review. Sellers and study authors frequently do not. In all six of the July 2026 reviews, the agency recorded that the nomination package left it unclear which form was being nominated, and evaluated both forms on its own initiative as a result.

Checking this takes one step. Compare the registry number and the molecular weight on the certificate against the name printed on the vial. If the name says free base and the numbers describe the acetate, the two documents are about different things.

Seven checks that take five minutes

Read the lot number first. A certificate describes one batch. If the lot number on the certificate is absent, or does not match the vial, it describes a different batch.

Read the letterhead. A certificate from the seller or its supplier is the seller's assurance about the seller's product. A third-party laboratory report is a different document, and the difference is on the letterhead rather than in the wording.

Read the date and compare it against the retest or expiry date. An old certificate on a current listing means the batch is old, the document has been reused, or both.

Check the form. Free base or acetate, and whether the registry number and molecular weight agree with the name.

Look for what is not listed. Purity alone means impurities, aggregates, microbial burden and endotoxin were not reported.

Read the methods column. A result without a stated method cannot be assessed, and different methods measure different things.

Note what the certificate covers. It describes bulk powder, not a finished sterile preparation. Sterility and endotoxin limits for an injectable product are established by the pharmacy that compounds it, and they are a separate set of records.

What a certificate can never tell you

It cannot tell you whether a substance may lawfully be used in a medication. That is a regulatory question and it is answered on the compound board, not on a test report.

It cannot tell you whether the compound works. No purity figure has ever established a clinical effect.

It cannot tell you that the vial in your hand contains what the document describes. It establishes what a laboratory found in a sample, and the chain from that sample to that vial is the part a certificate does not cover.

Sources

Each document below is named as it names itself, with the date printed on that document rather than the day it was read.

1. FDA Briefing Document for TB-500-Related Bulk Drug Substances, Pharmacy Compounding Advisory Committee — U.S. Food and Drug Administration, May 2026
2. FDA Briefing Document for BPC-157-Related Bulk Drug Substances, Pharmacy Compounding Advisory Committee — U.S. Food and Drug Administration, May 2026
3. FDA Briefing Document for KPV-Related Bulk Drug Substances, Pharmacy Compounding Advisory Committee — U.S. Food and Drug Administration, May 2026
4. FDA Briefing Document for Semax-Related Bulk Drug Substances, Pharmacy Compounding Advisory Committee — U.S. Food and Drug Administration, May 2026
5. Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act — U.S. Food and Drug Administration, May 2026