Methodology

Six assays, one certificate.

Every batch certificate reports the same panel. This page is what each assay measures, the method behind it, and the specific failure it rules out. For how a batch reaches this point, see the lab page.

How a batch gets released Certificates Common questions

The panel

What each assay actually establishes.

Analysis is performed by an independent laboratory, named on the certificate, on a sample drawn from the finished lot. We claim no accreditation for it, because none is on file — what is checkable is the name on the document.

Identity

HPLC + mass spec

Confirms the material in the vial is the peptide on the label.

Mass spectrometry measures the molecular weight of what is actually present and compares it against the theoretical mass for the published sequence. High-performance liquid chromatography corroborates it: a peptide has characteristic retention behaviour under a defined method, and a substituted compound does not match it.

What it rules out

Substitution — a different, cheaper peptide sold under the name of an expensive one. This is the failure mode that no amount of packaging can hide and no amount of branding can rule out.

Purity

HPLC

Reports how much of the peptide present is the target peptide.

Synthesis leaves behind close relatives of the intended molecule: deletion sequences missing a residue, truncated chains, incompletely deprotected fragments. HPLC separates them and reports the target as a proportion of total peak area. The measured figure for your lot is printed on that lot's certificate.

What it rules out

A lot carrying a heavy load of synthesis-related impurity. Purity is the number most often quoted and least often tied to a lot — which is exactly why we do not quote one on this site.

Net peptide content

HPLC

Reports how much of the powder in the vial is peptide at all.

A lyophilised cake is not pure peptide by mass. It also contains counter-ions from purification, residual water and salts. Content answers a different question from purity: purity asks how much of the peptide present is the target, content asks how much of what is in the vial is peptide in the first place.

What it rules out

The gap between the two. A lot can report high purity and still be substantially salt by weight — reporting only one of the two figures is the most common way a certificate flatters a batch.

Heavy metals

ICP-MS

Screens for elemental contamination.

Inductively coupled plasma mass spectrometry ionises the sample in a plasma torch and separates the resulting ions by mass, which makes it sensitive to metals at trace levels. Contamination here comes from reagents, catalysts and equipment rather than from the synthesis itself.

What it rules out

Metal carry-over from the production line. Nothing about a peptide's sequence predicts it, so it has to be measured rather than reasoned about.

Sterility

PCR

Screens the finished vial for microbial contamination.

Testing is done on the finished, filled vial rather than on bulk material, because the fill is one of the points where contamination is introduced.

What it rules out

Microbial contamination in the container you actually receive.

Endotoxin

USP <85>

Measures bacterial endotoxin.

Endotoxins are fragments of bacterial cell wall. They are heat-stable and they survive processes that kill the organism that produced them, so a vial can pass a sterility screen and still carry them. USP <85> is the compendial bacterial endotoxins test.

What it rules out

The assumption that sterile means clean. It is the assay most often left off a certificate, and the omission is rarely accidental.

Reading one

A certificate has five parts, and four of them are checks.

Most of the value in a Certificate of Analysis is in the header, not the results table. The results tell you what was measured; the header tells you whether it was measured on your material.

How to read a Certificate of Analysis
Section	Field	What to check
Header	Compound · lot	The compound name and the lot number. Check this against the lot printed on your vial — if they differ, the certificate is describing something else.
Header	Dates	Manufacture date and test date. The test date should fall after the manufacture date; a certificate tested before the lot existed is describing a different batch.
Header	Issuing lab	The laboratory that performed the analysis, named. A certificate with no identifiable lab on it cannot be corroborated by anyone.
Body	Assay rows	One row per assay: the specification the lot had to meet, the method used, and the result measured. A result with no specification beside it is a number without a pass mark.
Footer	Sign-off	The analyst or authorised signatory who released the report.

The single most useful check takes five seconds: does the lot number on the certificate match the lot number on the vial? A certificate that cannot be matched to a physical vial is a specimen document, whatever it says.

How to request the certificate for a batch

Open items

What this page still needs before it is complete.

Operator review required · Sterility method

The product detail panel currently prints “Sterility · PCR”. PCR-based rapid detection and the compendial sterility test (USP <71>) are different things. Confirm which is performed so both surfaces say the same thing.

We publish no site-wide release specification. Where the issuing laboratory states one, it is printed beside the result on the certificate itself — which is the only place a threshold means anything, because it is the one the lab actually applied.

The laboratory's full report — chromatogram included, where the lab prints one — is the PDF mirrored beside every published record. Nothing is summarised for you.

Operator review required · Retention samples

Whether a retained sample is kept from each lot, and for how long.

Operator review required · Retest dating

Whether lots carry a retest or expiry date, and how it is determined.

The limit of all of it

This panel establishes what a material is and what it is not contaminated with. It does not establish what a compound does in a living system, and it is not a safety assessment. Everything sold here is supplied for laboratory and research use only.

How to read a certificate of analysis Back to the lab Browse the catalog Ask about a batch

For laboratory and research use only · Not for human or veterinary consumption · Not evaluated by the FDA

Questions

What is the difference between identity testing and purity testing?

Identity asks whether the material is the compound named on the label; purity asks how much of the sample is that compound rather than something else. A sample can be unambiguously the right peptide and still be substantially something else by mass, which is why both run on every lot and both appear on the certificate.

What does HPLC actually measure?

High-performance liquid chromatography separates a sample into its components and reports each one as a proportion of the whole. The purity figure is the area of the peak belonging to the target compound against the total. It is a measurement of composition, and it says nothing about whether the material is fit for any particular use.

What the purity number means

Why is net peptide content reported separately from purity?

Because they answer different questions. Purity describes the fraction of the sample that is the target compound. Net peptide content describes how much peptide is actually in the vial once salts and residual water are excluded. A vial can be highly pure and still hold less peptide than the label claims.

Does a certificate of analysis expire?

The measurement does not — it describes the lot on the date it was tested, and that stays true. What a certificate cannot tell you is how the material has been handled since. It is a record of a moment, not a continuing guarantee.

Operator review required · Retest dating

Whether lots are retested after a set interval, and what that interval is. No retest policy is recorded, so none is described.