text: This assay was patented in 2006 by Randall Nelson, Peter Williams and Jennifer Reeve Krone. The idea first came about with the development of ELISA and RIA. An earlier patent method suggested tagging antigens or antibodies with stable isotopes or long-lived radioactive elements. But limitations to both methods called for a better detection methods of a protein or proteins. The invention combines antigen-antibody binding with a mass spectrometer which aids in identifying qualitatively and quantifying analytes respectively.
  An early MSIA experiment was done on a venom laced human blood sample for the Antigen myotoxin. The experiment was successful in that the mass spectrum resulting from the analysis showed a distinct response for myotoxin at the molecular weight corresponding to 4,822 Da (a). The m/z ratio at 5,242 Da (b) is the molecular weight of the modified variant H-myotoxina, used as an internal reference species. The figure of the mass spectrum is shown below.