An automatic analyzer cartridge, spinnable around a rotational axis, has aliquoting and metering chambers, a connecting duct there between, and a vent connected to the metering chamber and nearer to the rotational axis than the metering chamber. The metering chamber has side walls that taper away from a central region. Capillary action next to the side walls is greater than in the central region. A circular arc about the rotational axis passes through a duct entrance in the aliquoting chamber and a duct exit in the metering chamber. The cartridge has a downstream fluidic element which is part of a fluidic structure for processing a biological sample into the processed biological sample. A valve connects the metering chamber to the fluidic element, which is fluidically connected to the fluidic structure. The fluidic structure receives the biological sample and has a measurement structure for enabling measurement of the processed biological sample.