An apparatus and method for collecting whole blood and then separating it into components for subsequent use or storage. A self-contained bag set is used to collect the sample, which may then be placed into a device adapted to fit into a centrifuge for separation of components. Each component is then sequentially extracted according to density, with a sensor present in the device to control the operation of valves directing the collection of each component. Each component may then be separated into its own storage container.