What does peptide “gross weight” mean? How does it relate to peptide content and peptide purity?
Peptide “gross weight” refers to the actual weighed weight of the peptide. The gross weight includes the correct peptide, residual water, as well as peptide and non-peptide impurities that may be present and contribute to the weight. “Peptide content” is more specific and refers to the amount of correct peptide relative to everything else that contributes to the gross weight of the sample, such as residual water, peptide impurities, and non-peptide impurities. “Peptide content” is not obtained from weighing the sample. Instead, it is estimated from the combined data from amino acid analysis and from peptide purity. Peptide content is affected by the amount of water and salts present in the peptide sample. “Peptide purity” refers to the amount of correct peptide relative to all peptide and non-peptide impurities (except water and salts) that are detected by the assay method. Normally, peptide purity is determined by analytical RP-HPLC and detected by the absorbance at 215 nm. Peptide pu
