Multiplexed analyses of test samples

A method for detecting a target molecule that may be present in a test sample, the method comprising:

• (a) contacting a test sample with an aptamer having a specific affinity for a target molecule, wherein an aptamer affinity complex is formed by the interaction of an aptamer with its target molecule, if said target molecule is present in said test sample, wherein said aptamer binds to said target molecule through non-Watson Crick interactions, and wherein the aptamer has been previously selected to have binding affinity for the target molecule;
• (b) after equilibration of aptamer affinity complex formation, exposing said test sample to conditions that kinetically challenge components of said test sample;
• (c) at any point prior to (d), contacting said aptamer affinity complex with a labeling agent;
• and
• (d) detecting and/or quantifying the aptamer affinity complex partitioned from the remainder of the test sample,
• wherein the kinetic challenge comprises (i) introducing a competitor molecule to the test sample, or (ii) the capture of aptamer affinity complexes on a solid support followed by washing with competitor molecules present in the wash solution, and wherein the competitor molecule is selected from the group consisting of an oligonucleotide, a polyanion, an abasic phosphodiester polymer, a dNTP, and a polydextran.