HPLC: how pure
High-performance liquid chromatography separates the contents of a sample, and a UV detector records each component as a peak. The purity figure is the main peak's share of all the peaks, usually measured at 220 nm.
What it proves: how much of the peptide material is the target sequence.
What it does not prove: what the main peak is. Two different peptides can both give one clean peak.
Our purity specification is stated on each product page.
Mass spectrometry: which molecule
Mass spectrometry measures the mass of the molecules in the sample. The measured mass should match the mass worked out from the sequence.
What it proves: the molecule is the one named.
What it does not prove: how much else is in the sample.
That is why a certificate needs both tests, and why we will not supply a batch that has only one.
Other results you may see
- Net peptide content: the share of the powder that is peptide, the rest being water and counter-ion.
- Water content and counter-ion content.
- Endotoxin: only where the manufacturer tested for it. If the line is not on the certificate, it was not tested.
Who does the testing
The manufacturer tests every batch; that is the certificate you receive. We do not claim independent testing unless a report from a named laboratory is published with the batch.
Check it yourself
You do not have to take a certificate on trust.
- Work out the expected mass from the sequence with our peptide calculator and compare it with the certificate.
- Ask for the chromatogram as well as the purity figure.
- If the certificate names a laboratory and a report number, the laboratory can usually confirm it.