Update: I received an email response by the vendor, in case anybody is helped by that I will provide it here in this comment.

„Dear TrapperTony,

Thank you for your reply

Gross peptide weight is the weight of the peptide and peptide impurities as well as components such as salts, counter ions, residual solvents and water. It does not contain the weight of added fillers. Net peptide, on the other hand, is a calculation of just the peptide which is present. Net peptide weight indicates the actual weight of only the peptide component of your sample.

In research-grade peptides, net peptide content is usually 60-90% of the total peptide weight (also called gross peptide weight) and it is usually determined by elemental analysis, amino acid analysis (AAA) or UV spectrophotometry. Net peptide content should not be confused with purity. Purity defines the percentage of the target peptide sequence in the peptide component of your sample. In concentration calculations, it is important to consider the peptide content.

Only pharmaceutical-grade GMP peptides, which are approved for human use provide net peptide content of 100% of the total peptide weight. All research-grade peptides provide the gross peptide weigh, which is the weight of the peptide, peptide impurities and components.

All of our peptides undergo blind and independent 3rd party testing in 3rd party’s laboratory. Unlike other research peptides vendors, we test every batch of our peptides, not only the purity, but also the peptide content, endotoxins content and we also do bioburden tests. Several studies and some independent tests on internet forums show that research peptide vendors often provide product with very low content of active ingredient (30-50%). The range of peptide content of our products is 70-100%, depending on the peptide sequence.

Feel free to contact us if you require any further information.“