The part most suppliers omit
Our certificates test identity and purity, not fill weight. Each one names the compound, the lot and the analyst, and prints the chromatogram it was read from. What it does not do is weigh the powder in your vial, and we would rather say so than let the word “tested” imply a check we did not run.
Key facts
- Purity floor
- 99.99% HPLC-UV, measured per lot
- Identity check
- ESI mass spectrometry, every lot
- Who tests it
- An external laboratory, not us
- Certificates published
- 21, linked from the product page
- Detection wavelength
- 214 nm, area under the curve
- Dispatch
- Same day, every order
Two tests, and what each proves
Purity without identity tells you the vial is 98% something. Identity without purity tells you the right molecule is in there, at an unknown concentration. Both, or the result is incomplete.
HPLC-UV
How much of the vial is the peptide.
Reverse-phase chromatography with UV detection at 214 nm separates the peptide from related impurities. Each lot must reach 99.99% by area under the curve.
On the certificate: Column type, mobile phase, gradient, and the printed chromatogram.
ESI-MS
Whether it is the molecule on the label.
Electrospray ionisation mass spectrometry matches the observed mass against the theoretical mass of the named peptide, within standard tolerance.
On the certificate: Observed mass, expected mass, and the tolerance applied.
What appears on every certificate
A certificate missing any of these is not a certificate. It is a claim with a letterhead. Ours are the unedited documents for the exact lot dispatched.
- Compound name, lot number and synthesis date
- HPLC-UV purity result, measured rather than specified
- ESI mass spectrometry identity confirmation
- Test method, column conditions and mobile phase
- The printed chromatogram, not a summary of it
- Signed and dated by the analyst who ran it
What holds a lot back
An identity failure means the wrong molecule, and the lot does not ship. Purity is the other half: the chromatogram separates the material into its components and measures each one, so the figure on the certificate is a measurement rather than an estimate. Fill weight is not part of this analysis.
Does not ship
- HPLC-UV purity below 98.0% on the independent test
- Mass spectrometry identity outside expected tolerance
- Visual defects in the lyophilised cake: cracks, collapse, discolouration
- Cap seal failure or vacuum loss at inspection
- Documentation mismatch between vial, certificate and release log
Ships, with the certificate saying so
- A measured fill quantity below the stated specification, disclosed on the certificate
- Purity at the floor rather than comfortably above it. The measured figure is printed, not rounded up
Quietly shipping borderline material against a clean-looking page is how the wider grey market damages researcher trust.
Storage, packaging and traceability
- Storage
- Lyophilised vials are held at −20°C in a dedicated peptide freezer until dispatch, with temperature logged continuously. Orders are not shipped insulated. Lyophilised material is stable in transit.
- Packaging
- Shock-absorbing void fill, and plain outer packaging with no branding and no compound name visible.
- Traceability
- The lot number on the vial matches the certificate, the dispatch note and our internal release log.
If a lot ever arrives not as described, email admin@uk-peptides.org with the lot number and we will investigate and replace at our cost.
Questions asked before ordering
- Who tests UK Peptides material?
- An external analytical laboratory, not us. Every lot is sent out for HPLC-UV purity quantification and ESI mass spectrometry identity confirmation before it is released to the catalogue. We do not run our own analysis on material we sell.
- What purity do you release at?
- 99.99% by HPLC-UV, measured as area under the curve at 214 nm. The figure on each certificate is the measured result for that specific lot, not a specification copied from a supplier sheet.
- What do your certificates actually test?
- Every peptide in the catalogue has one, published unedited and linked from its product page, except new products still waiting on their lab report (currently Tesamorelin and PT-141). They are purity and identity certificates: HPLC-UV for purity, mass spectrometry for identity, each naming the lot and the analyst who signed it. They do not measure the fill weight of the vial. Bacteriostatic water is a solvent rather than a peptide, so there is no HPLC certificate to issue for it.
- Is the certificate matched to the vial I receive?
- The lot number printed on the vial matches the lot on the certificate and on the dispatch note. If the two ever disagree, email your order ID and we will send the lot-matched documentation we hold.