Method for determining the concentration of a molecule

Abstract

The present invention relates to a method for determining the concentration of a first molecule having a chemical structure, which contains a first peptide sequence comprising: (a) obtaining a sample containing the first molecule, (b) providing a reference sample which contains a second molecule having a certain concentration and chemical structure, which contains a second peptide sequence, wherein the chemical structure of the second molecule only differs from the structure of the first molecule in one or more permutations in the first peptide sequence, (c) combining the reference sample and the sample containing the first molecule, (d) identifying at least one fragment peak in a mass spectrum (MS) of the first molecule and the second molecule, wherein the mass difference of the fragment peaks is only caused by the permutation of the at least two different amino acids, and (e) determining the concentration of the first molecule relative to the certain concentration of the second molecule by comparing of the identified peaks.

Dependencies are inferred from the claim text.