an analytical assay reaction cartridge having a housing that comprises a reaction chamber, an inlet for introducing a liquid test sample into the reaction chamber, and a sample read window formed through a portion of the reaction chamber, wherein the sample read window has a shape with an outer edge that surrounds the shape of the sample read window that extends through the portion of the reaction chamber;

at least one solid analytical reagent, wherein the solid analytical reagent comprises magnetic beads coated with at least one anti-human red blood cell antibody, and wherein the solid analytical reagent is soluble in a liquid reagent; and

a magnetic assembly comprising a permanent magnet; and

wherein at least one contact point of the magnetic assembly is disposed substantially adjacent to at least one contact point on the outer edge of the sample read window of the analytical assay reaction cartridge.