Quality
A number you can
check yourself.
Purity claims are cheap. What makes one meaningful is the method behind it, the laboratory that ran it, and whether you can read the raw result rather than a summary of it. Here is all three.
Assays
Four assays, every lot, no exceptions.
A lot that fails any one of these is not offered for sale, is not quietly blended into another lot, and is not sold at a discount as a lower grade.
- 01
RP-HPLC
Reverse-phase high-performance liquid chromatography
Reports: Chromatographic purity, % main peak by area
C18 column, water/acetonitrile gradient with 0.1% TFA, UV detection at 214 nm — the wavelength of the peptide bond itself, so every residue contributes to the signal rather than only the aromatic ones. Purity is main-peak area over total integrated area.
- 02
LC-MS / ESI-MS
Liquid chromatography with electrospray mass spectrometry
Reports: Observed mass vs theoretical mass
Confirms the material is the compound named on the vial. The observed monoisotopic mass is compared against the theoretical mass calculated from the stated sequence; a deviation outside tolerance fails the lot regardless of how clean the chromatogram looks.
- 03
Nitrogen determination
Net peptide content by elemental nitrogen analysis
Reports: Net peptide content, % w/w
Lyophilized peptide is not pure peptide. It carries counter-ions, residual solvent, and water. This assay establishes how much of the vial mass is actually peptide, so a stated milligram figure means what it says.
- 04
Karl Fischer
Coulometric water content determination
Reports: Residual moisture, % w/w
Residual water drives hydrolysis and shortens shelf life. Measuring it is how we can state a storage life rather than estimate one.
Disclosure
What the certificate says — and what it does not.
A certificate that only lists what passed is marketing. Ours states the boundaries of the testing too, because knowing what was not measured matters as much as knowing what was.
- Chromatographic purityReported as measured, to one decimal place
- Observed massReported with the theoretical value beside it
- Net peptide contentReported as measured
- Residual moistureReported as measured
- Testing laboratoryNamed on the certificate
- Date of analysisStated on the certificate
- Lot numberPrinted on the vial and the certificate
- SterilityNot tested — material is not supplied sterile
- EndotoxinNot tested unless separately commissioned
Material is supplied non-sterile as a research chemical. If your protocol requires sterility or endotoxin data, commission it independently — do not infer it from these certificates.
Chain of custody
Material is received, quarantined, and sampled before it enters sellable stock. Samples go to an independent laboratory that is not paid by result and has no commercial interest in the outcome. The certificate is issued against the lot number, the lot number is printed on the vial, and the certificate is published before the lot is listed.
If a lot underperforms its specification, the certificate still goes up — attached to a lot that is not for sale. We would rather publish a failure than quietly delete it.