What a Certificate of Analysis Actually Tells You

A certificate of analysis is the most useful document attached to a batch. It is also the one people skim hardest.

Most readers find one number, the purity percentage, and stop. That number means something. But on its own it answers a much narrower question than people assume.

This is our guide to reading the whole document. Every batch we release is tested by an independent analytical lab and the resulting reports are published in full.

A certificate answers two separate questions

Testing a lab-made peptide tackles two separate problems. They need different methods.

The first is identity. Is the stuff in this vial the compound on the label?

A purity figure cannot answer that. A vial could hold one very pure substance that is not what you ordered. A purity test would still call it clean. Identity comes from weighing the molecule.

The second is composition. Of what is there, how much is the target and how much is something else? That is what chromatography measures.

A certificate that reports only one of the two is incomplete. Both appear on the reports we publish.

Identity: mass spectrometry

Mass spectrometry weighs the molecule very precisely. That measured weight is then compared against the weight the compound's sequence and formula predict.

For a peptide that is a strong check. The weight follows directly from what the molecule is made of. A missing bead. An unintended change. A different partner ion. Each shifts the weight in a way that is easy to spot. A report gives the weight it measured and the weight it expected. When those match, the molecule is what the label claims.

This is why the molecular weight and formula printed on every product page matter. They are the values the test is checked against. Both appear in the quick facts panel on each compound page.

Purity: high-performance liquid chromatography

HPLC pushes the dissolved sample through a packed tube under pressure. The parts separate by how hard they grip the packing. Each comes out at its own time, and a detector logs a signal as it passes.

The output is a chromatogram: a baseline with peaks rising from it. The target compound produces the main peak. Everything else that the detector registers produces smaller peaks.

Purity is normally reported as percentage area. That is the area under the main peak as a share of the area under all the peaks. So 99 percent area means 99 percent of the detected signal came from the target compound.

Two points about that figure are worth stating plainly.

First, it only describes what the detector can see. Anything that does not absorb at the chosen wavelength adds nothing to the chromatogram. So it adds nothing to the percentage. Water and salts are the usual examples.

Second, it is a proportion, not an absolute quantity. It tells you how the detected material is divided up, not how much peptide is in the vial.

Net peptide content: the figure that is often missing

Net peptide content answers what percentage area cannot. Of the total weight in the vial, how much is actually peptide?

The rest is not contamination. A lab-made peptide usually comes as a salt, paired with a partner ion such as acetate or trifluoroacetate. Freeze-dried powder also holds a little water. Both add real weight.

The result is arithmetic. A vial can be 99 percent pure by HPLC and still hold noticeably less peptide than the label weight. There is no contradiction. The two figures are measuring different things. Anyone working out a strength from a vial weight is relying on net peptide content, whether they know it or not.

This is the number we would encourage readers to look for on any supplier's documentation, not only ours.

Retention time as a second identity signal

Next to the purity percentage, a chromatogram gives the retention time of the main peak. Under fixed conditions, the same compound always takes the same time.

It functions as a corroborating identity check. So a good batch passes two separate checks. Its main peak comes out at the expected time, and its weight matches the value the sequence predicts.

What the impurity peaks represent

The small peaks are mostly a record of how the molecule was made.

A chain gets built one bead at a time, and no joining step works perfectly every time. Chains that miss a bead, and chains that stopped early, are both near-misses of the target. Both show up as small peaks close to the main one.

Purification exists to strip those out. So the purity figure is largely a measure of how well that clean-up worked.

Batch numbers and traceability

A certificate is only useful if it can be tied to the material in front of you. That link is the batch number.

The batch number on a report should match the one on your vial. If it does, the result describes that exact production run. If it does not, the document is about different material, however good its numbers look.

Writing batch numbers down with your data is what makes results traceable. If something needs re-examining later, the batch number is what links it back to the tested material.

Independent verification

A test result is only as good as the lab that issued it. A lab with money riding on the outcome is in an awkward position.

Our finished vials go to Janoshik Analytical, an independent lab with no money riding on the result.

Every report they issue carries a unique key, printed at the bottom. Enter that key on the lab's own page. It confirms two things. The report came from them, and nobody has altered it.

We publish the reports rather than sending them on request. A document you can check beats an assurance you cannot.

A short reading order

Working through a certificate in this order tends to be the most efficient.

1. 1.Check the batch number against the vial label.
2. 2.Confirm the compound name and the theoretical mass match the product page.
3. 3.Read the observed mass from the mass spectrometry section and compare it to the theoretical value.
4. 4.Read the purity as percentage area, and note the detection wavelength it was measured at.
5. 5.Look for net peptide content, and note its absence if it is not reported.
6. 6.Check the retention time against the reference value.
7. 7.Verify the report with the issuing lab using its verification key.

Seven checks. After them, the material in front of you is tested rather than just described.

Why we publish every batch

Paperwork is the part of this business you can actually check. A purity claim written in prose is an assertion. A batch report from a named independent lab, with a key you can check, is evidence.

Our published reports are filed by compound and batch. The maker and batch number on each report match the label on the vial we send. Where a compound has no published report yet, it is simply absent. We do not show another batch's document in its place.

Everything we sell is for lab research only. It is not a medicine, and it is not for people or animals to take.