Abstract: A gel filtration plate designed to remove unincorporated dye terminator from a series of reaction mixtures in a nucleic acid sequencing operation is joined to an injection plate designed for insertion into a sequencing apparatus through an adaptor assembly that allows the two plates to be centrifuged together, thereby simultaneously purifying the reaction mixtures and collecting them in the receptacles that will be placed directly in the sequencer. The adaptor avoids the use of an intermediary collection plate and the need to transfer reaction mixtures from each well of the collection plate to each well of the injection plate.