Apparatus and methods for separating blood components are disclosed in which an apparatus for separating blood generally includes a tube defining a channel and configured for receiving a quantity of blood and a float contained within the tube and having a density which is predefined so that the float is maintained at equilibrium between a first layer formed from a first fractional component of the blood and a second layer formed from a second fractional component of the blood. Upon completion of the centrifugation, the first layer may be removed from the tube while the float isolates the second layer from the first layer.