Abstract: A method of assaying for an analyte which occurs at least partially bound as a complex with its soluble receptor or binding protein, the method comprising the steps of: i) mixing a biological fluid serum sample containing the analyte to be determined with a detergent for dissociating said complex, ii) mixing the sample from step i) with reagents, including a specific binding partner of the analyte for binding to the analyte, for performing a specific binding assay for the analyte, iii) and mixing the sample from step i) with a sequestrant for the detergent, whereby the binding of step ii) is performed in the presence of the sequestrant.

Abstract: A substrate with a plurality of microchannels is movably deployed with other movable objects that will load sample into the microchannels, stimulate molecular migration, read the results of the migration, remove and replace the substrate, and prepare for a new run. The other objects include a gripper for engaging and moving the substrate, an electrode array of fine wires suitable for fitting into the microchannels for electromigration, and a scanning detector for reading migration results. A sequence of automatic operations is established so that one substrate after another may be moved into position, loaded with sample, stimulated for molecular migration, read with a beam, and then removed and replaced with a fresh substrate.