Abstract: A method whereby a sample handler moves and positions racks, containing sample tubes, in an analytical instrument. The sample handler has an in-feed and out-feed that advance sample tube racks using a walking beam mechanism. The racks are seated within the in-feed and are transported onto a cross-feed. The racks and tubes contained thereon are moved past detection devices that identify the samples and measure various properties thereof. Thereafter, the cross-feed moves the racks to a position behind the out-feed where the walking beam mechanism moves the tube racks out of the analytical instrument.