Patent ID: 7303888

Claim:
A method for quantifying the relative amount of one or more analytes present in a specimen, comprising the steps of: a. combining said specimen with a known amount of internal reference species (IRS) if the specimen does not already contain one; b. capturing and isolating at least one of the one or more analytes and said IRS using an affinity reagent having a specific affinity for the one or more analytes and the IRS where the affinity reagent includes at least one antibody immobilized onto a solid substrate; c. releasing the isolated one or more analytes and IRS by eluting the one or more analytes and the IRS from said at least one antibody; d. adding a laser desorption/ionization agent to the released one or more analytes and IRS to form a mass spectrometric mixture; and e. quantifying the one or more analytes by using only single dimension mass spectrometric analysis to resolve distinct signals for the one or more analytes and said IRS to determine the amount of the captured one or more analytes relative to the IRS.