A primary antibody bead suspension for an enzyme-linked immunoassay ("ELISA") procedure is formed of a quantity of primary antibody coated magnetic beads (3) uniformly dispersed and held in suspension (9) by a thixotropic non-Newtonian fluid (1). To remove the thixotropic non-Newtonian fluid prior to application in the ELISA procedure, a magnet (12) is placed against the side of the non-magnetic vessel (9) holding the suspension to draw the magnetic beads against the side while the thixotropic fluid is washed away by pumping (14,16,15& 17) and replaced by a saline buffer solution.