Patent ID: 7396688

Claim:
A method for determining the absolute quantity of a target biopolymer in a crude solution, comprising the steps of: (a) adding a known quantity of a calibrated analog of said target biopolymer to said crude solution, wherein said analog is the target polypeptide, a unique segment or a fragment thereof, and wherein one of said analog and said target biopolymer is isotope labeled; (b) treating the target biopolymer and analog with a fragmenting activity to generate a plurality of corresponding biopolymer and analog fragment pairs in said crude solution; (c) fractionating the crude solution produced in step (b) by a chromatopraphic technique to resolve said plurality of fragment pairs produced in step (b); (d) determining by mass spectrometric analysis of a fraction in step (c) the ratio of a selected target biopolymer to its corresponding analog; and (e) calculating, from said ratio and said known quantity of said analog, the absolute quantity of the target biopolymer in the mixture.