Abstract: A multicuvette rotor for use in a centrifugal analyzer defines a circumferential array of elongated radially extending cuvettes. Each elongated cuvette defines a first chamber for receiving a first reactant and a loading port through which the first reactant is introduced into the first chamber region, a second chamber region for receiving a second reactant and a loading port through which the second reactant is introduced into the second chamber region, and divider structure between the first and second chamber regions that has a ramp surface and a ramp crest spaced from the ceiling surface of the cuvette so that a transfer passage between the first and second chamber regions is defined through which the first reactant may be flowed into the second chamber region for forming a reaction product with the second reactant.