MASS SPECTROMETRIC ANALYSIS

摘要

A method for assaying for a target analyte, which method comprises: (a) providing a plurality of samples which may comprise the target analyle, wherein each sample is differentially labelled with a mass label or a combination of mass labels, wherein the mass labels are from a set of mass labels, wherein each mass label is an isobaric mass label comprising a mass spectrometrically distinct mass marker group, such that the samples can be distinguished by mass spectrometry; (b) mixing the plurality of labelled samples to produce an analysis mixture and introducing the analysis mixture into a mass spectrometer; (c) selecting ions having a first mass to charge ratio equivalent to an ion of the target analyte labelled with a specific number of mass labels; (d) fragmenting ions of the first mass to charge ratio into a plurality of fragment ions, wherein a proportion of the plurality of fragment ions comprise at least one intact mass label; (e) selecting ions of a second mass to charge ratio equivalent to an ion of a fragment of the target analyte comprising at least one intact mass label; (f) fragmenting ions of the second mass to charge ratio into a plurality of further fragment ions, wherein a proportion of the further fragment ions are ions of the mass marker groups; (g) producing a mass spectrum of the further fragment ions produced in step (f); and (h) determining from the mass spectrum the quantity of the target analyte in each sample.