Methods for detecting a plurality of analytes by mass spectrometry

A method for detecting one or more target analytes, comprising:

• (a) contacting one or more target analytes with a set of first and second binding reagents under conditions sufficient for binding of a target analyte with said first and second binding reagents, each of said first binding reagents comprising a cleavage-inducing moiety and a target binding moiety, each of said second binding reagents comprising a tagged probe having a mass modifier region attached to a target binding moiety by a cleavable linkage, the mass modifier region of each second binding reagent having a unique mass and said cleavable linkage being susceptible to cleavage when in proximity to said cleavage-inducing moiety;
• (b) activating said cleavage-inducing moieties to cleave the cleavable linkages in proximity thereof so that mass modifier regions are released, and detecting the unique masses of the released mass modifier regions to determine each of the one or more target analytes.