Quality & testing

What is measured, and what is recorded

Every lot is tested before it is released, and the figures that come back belong to that lot rather than to the compound in the abstract. This page sets out the methods, the release sequence and the storage specification.

Liquid chromatograph coupled to a mass spectrometer on a laboratory bench

Representative trace

HPLC-UV · 214 nm

A single dominant peak on a flat baseline. Illustrative of the method; the trace for a given lot is on its certificate.

≥98%: purity specification
214 nm: HPLC-UV detection
Per lot: certificate of analysis
On dispatch: lot recorded to the order

Analytical methods

6 tests

HPLC-UV

Purity214 nm

Reverse-phase high performance liquid chromatography with ultraviolet detection at 214 nm, the wavelength at which the peptide bond absorbs. Purity is reported as the area of the main peak as a percentage of total integrated peak area. The specification is ≥98%, and the figure obtained for the specific lot is stated on its certificate rather than the specification being restated.

LC-MS

IdentityESI

Liquid chromatography coupled to mass spectrometry, confirming the observed mass against the mass calculated from the sequence. A lot is not released unless the observed and expected masses agree within the tolerance stated on the certificate.

Peptide content

Net peptide massper vial

The proportion of the vial contents that is peptide rather than counter-ion, residual water or salts. This matters when preparing a solution to a known concentration: a vial labelled 10 mg gross does not contain 10 mg of peptide, and the certificate states the figure for the lot.

Water content

Residual moistureKarl Fischer

Residual water left in the cake after lyophilisation. It is reported because it is part of the mass that is not peptide, and because a cake that has taken up moisture is the first sign of a seal that has not held.

Counter-ion

Salt formIC

Which salt the peptide was isolated as — most often acetate, sometimes trifluoroacetate — and at what level. The salt form is stated on the certificate because it changes the net peptide content and, for some assays, the result.

Appearance

Physical statevisual

Visual inspection against the specification of a white lyophilised powder or cake. Discolouration or a collapsed cake is a rejection at goods-in and the lot is not released.

Release

Goods-in
The consignment is checked against the purchase order and the vials against the appearance specification. A lot that fails here is quarantined rather than shelved.
Certificate received
The certificate of analysis for that lot is obtained from the manufacturer. A lot with no certificate is not a lot that can be sold; it is stock with no provenance.
Specification checked
Each figure on the certificate is read against the published specification — purity, mass, peptide content, appearance. A disagreement stops the lot here.
Released
Only then can the lot be assigned to an order line. Unreleased lots are invisible to the ordering system, so material cannot be dispatched against a batch whose certificate has not been seen.
Recorded on dispatch
The lot number is written to the order line at the point of dispatch, so the certificate for material supplied years ago can be produced without inferring which batch was in stock at the time.

Capped vials held in a rack on a laboratory bench

Lot numbers and certificates

A certificate belongs to a lot, not to a compound. The purity of a named compound in the abstract is not a meaningful figure; the purity of a specific synthesis, tested on a specific date, is.

Retrieve one from certificate lookup using the lot number printed on the vial, or from the order history in your account.

Storage and handling

Form as supplied	White lyophilised powder, sealed under an aluminium crimp cap
Storage specification	−20 °C, protected from light and moisture
Short-term handling	Shipped at ambient temperature in insulated packaging, as is standard for lyophilised material
On receipt	Transfer to −20 °C promptly and allow sealed vials to reach room temperature before opening, so atmospheric moisture does not condense onto the contents
Shelf life	Stated on the certificate for the lot

Why the figures are per lot

Two syntheses of the same sequence are not the same material. They differ in purity, in what the impurities are, in counter-ion and in residual water, and any of those can change a result.

Publishing a single number against a compound name would be tidier and would mean nothing. The specification states what a lot must meet to be released; the certificate states what the lot in front of you actually measured.

Research insight

Recent literature

All records →

About this list

Records are retrieved from PubMed and listed as a bibliography. Titles are reproduced as published. A citation records what has been studied; it is not a statement about the material supplied here, and nothing in this list is an indication of use.

Last retrieved 2026-10-12

Research Use Only. Not for human or veterinary use.

These materials are supplied to laboratories and research organisations as reagents. They are not medicines, are not supplied for administration to humans or animals, and must not be resold for those purposes.