Rapid mass spectrometric immunoassay methods for detecting and/or quantifying antibody and antigen analytes utilizing affinity capture to isolate the analytes and internal reference species (for quantification) followed by mass spectrometric analysis of the isolated analyte/internal reference species. Quantification is obtained by normalizing and calibrating obtained mass spectrum against the mass spectrum obtained for an antibody/antigen of known concentration.
 The present invention relates to a new and useful immunoassay and more specifically to new and improved mass spectrometric immunoassay processes for the detection and/or quantification of one or more antigens or antibodies in a single determining immunoassay. Hereinafter, singular terms are intended to include plural.
 Financial Assistance for some of the work reported herein was provided by the United States Department of Energy under Grant number DEFG02-91ER61127. The United States government may have certain rights to this invention.