Net peptide content is the percentage of actual peptide material relative to non-peptidic components such as moisture and counterions. It is different from peptide purity and is especially important when calculating actual peptide mass in a lyophilized sample.
Even under careful lyophilization conditions, peptides can retain varying amounts of bound water and counterions. This is especially true for hydrophilic peptides. As a result, the material weighed from the vial is not always identical to the true peptide mass.
That means a sample can be high purity by HPLC but still have a lower net peptide content by weight.
Net peptide content can vary from batch to batch depending on sequence, purification history, and lyophilization conditions.
Net peptide content is commonly determined by amino acid analysis. This type of measurement is useful when the actual peptide amount must be known more precisely than HPLC purity alone can provide.
If you are preparing a quantitative assay, comparing batches, or calculating exact peptide concentration from weighed powder, net peptide content is often more useful than purity alone.
Analyze your sequence to better understand peptide behavior:
If you require net peptide content analysis or help interpreting peptide mass versus content, please email sales@lifetein.com.