Testing Methodology

Three different numbers

Purity figures on this site answer three separate questions and are never used interchangeably:

• >99% is a specification. It is the release threshold we set. It is not a measurement and no laboratory reported it. A batch that does not meet it is rejected.
• A certificate figure is a measurement. It is what a named laboratory found in one named lot, on a stated date, by a stated method. It relates to the sample as received and to nothing else.
• ≥98% is the industry norm and appears on this site only where we are describing the sector, never as a claim about our own material.

Who runs the tests

Batch analysis is performed by an external analytical laboratory, not in house. Testing your own product and publishing the result is the weakest possible form of the claim, and it is the form most of this sector uses.

Certificates currently published on this site were issued by SideChain Analytics. Each certificate carries the laboratory's own report identifier and, where the laboratory publishes one, a link to its own verification page so the result can be confirmed against the laboratory rather than against us.

If you would rather not take our laboratory's word for it either, our directory of peptide testing laboratories lists places you can send a vial yourself. No listing in it is paid for, and it includes laboratories we have never used.

The methods

Published certificates report results by HPLC-MS/MS.

• Reverse-phase HPLC establishes purity. The sample is separated on a chromatographic column and the target peak is expressed as a percentage of total integrated peak area. This answers "how much of what is in the vial is the target compound".
• Mass spectrometry establishes identity. The observed mass is compared against the expected mass for the sequence. A high HPLC purity figure on its own says the vial contains mostly one thing; it does not say that thing is the peptide on the label. Purity without identity is the failure mode worth knowing about.

Upstream of testing, material is produced by solid-phase peptide synthesis and purified by preparative HPLC. Synthesis and purification are not tests and are not presented as ones.

What a certificate does not establish

• It covers one lot, not a product line. A certificate for one fill does not describe a different fill of the same compound. Where we show a certificate on the page for a different vial size, the page says which lot the document covers and labels the figure accordingly, rather than presenting it as that vial's own result.
• Percentage purity is not net peptide content. Chromatographic purity does not account for counterion, residual solvent and water content, so the mass of peptide in a vial is lower than the labelled fill multiplied by the purity figure.
• It says nothing about safety or suitability for any use in humans or animals. These are research materials. A purity figure is an analytical result, not a safety finding.
• It is a snapshot, not a shelf life. The result describes the sample at the time it was analysed.

How much of the catalogue is covered

Honest coverage numbers, derived from our own records rather than written by hand:

Most of the catalogue does not yet carry a published certificate. That is a real gap and we would rather state it here than let the presence of a certificates page imply a coverage we do not have. Our batch history dataset lists every SKU including the ones with no certificate, for the same reason: dropping those rows would make a transparency document into a marketing one.

Checking a certificate against the vial

Every product page prints a batch number derived from the compound and the vial strength. Every certificate prints a lot number transcribed from the laboratory's document. The two are produced independently, so comparing them is a check you can run without trusting us at any step.

Certificates are published as page images rather than as source PDFs. A certificate is the easiest document on this site to forge: hand over the file and anyone can change the laboratory name and the purity figure while keeping an accredited laboratory's letterhead. The images carry everything the document states, and the laboratory's own verification link is what makes the result checkable somewhere we do not control. View published certificates.