Abstract: The present invention is a method to quantitate proteins associated with a disease or disease state comprising the steps of isolating at least two target proteins from a test sample, combining the target proteins with a known concentration of a concatenated oligopeptide standard and a proteinase to form peptide fragments and standard peptide fragments. The concatenated oligopeptide standard comprising at least one peptide having an amino acid sequence substantially similar to a unique amino acid sequence of a peptide fragment of the two target proteins. The peptides for each of the target proteins are joined by proteinase cleavage sites to form the concatenated oligopeptide. Quantitation of the target proteins is determined by comparison of the peptide fragments to the standard peptide fragments using mass spectroscopy.