An automatic analyzer cartridge, spinnable about a rotational axis, has fluid and aliquoting chambers, a metering chamber connected to a vent that is nearer to the rotational axis than the metering chamber, first and second ducts connecting the fluid and aliquoting chambers, and the metering and aliquoting chambers, respectively. Metering chamber side walls taper away from a central region, wherein capillary action next to the walls is greater than in the central region. Fluid flows to the metering chamber using capillary action via the second duct that has an entrance and exit in the aliquoting and metering chambers, respectively; the exit being closer to the rotational axis than the entrance. A downstream fluidic element connects to the metering chamber via a valve. A fluidic structure receives and processes a biological sample into the processed biological sample and has a measurement structure that enables measurement of the processed biological sample.