Disclosed herein is a modular test tube rack. The rack contains multiple sub-racks that can be coupled together to form the test tube rack. The sub-rack can be designed to fit into a variety of scientific instrumentation including a fixed rotor centrifuge. The assembled test tube rack can be of a format and size that allows use of standard array pipetters. Thus, a system is provided allowing use of standard array pipetters and high g centrifugation.