Qualitative and quantitative electrochemiluminescent assays for analytes of interest present in multicomponent liquids are provided. These methods comprise contacting a sample with a reagent labeled with an electrochemiluminescent chemical moiety and capable of combining with the analyte of interest, exposing the resulting sample to electrochemical energy and detecting electromagnetic radiation emitted by the electrochemiluminescent chemical moiety.Further provided are methods for detecting and identifying the presence of a multiplicity of analytes in a liquid food or food homogenate. These methods comprise immersing a diagnostic reagent holder, provided with a multiplicity of reagents, into the food or food homogenate, removing the diagnostic reagent holder from the liquid food or food homogenate, and detecting and identifying the presence of a multiplicity of analytes of interest bound to the diagnostic reagent holder, thereby detecting and identifying the presence of a multiplicity of analytes of interest in the food or food homogenate.The invention further provides an enzyme immunoassay for coliform bacteria. This assay comprises inoculating a sample into a suitable medium for coliform reproduction, immobilizing coliforms present in the medium to a suitable surface, treating the surface with an antibody directed to the immobilized coliforms and detecting the presence of the immobilized coliforms immobilized to a suitable surface.