Non-related molecular probes have been employed for the development of competitive equilibrium binding assays for the herbicide 2,4-dichlorophenoxyacetic acid based on a molecularly imprinted polymer. The assays are analogous to competitive solid-phase immunoassays, except that imprinted polymer particles were substituted for the antibodies and non-related molecular probes for the labeled antigen. Three different formats were studied which are based on fluorescence, chemiluminescence or electrochemical detection. Specificity and sensitivity of such systems may be on a par with radioligand displacement assays using the same molecularly imprinted polymer and radiolabeled analyte, providing that the probe binds to the imprinted sites with a certain degree of specificity.