1. A method for determining the sequence of a nucleic acid, comprising the steps of: a) generating at least two conditioned, base-specifically terminated nucleic acid fragments from a nucleic acid to be sequenced; b) determining the molecular weight value of each base-specifically terminated fragment by mass spectrometry, wherein the molecular weight values of at least two base-specifically terminated fragments are determined concurrently; and c) determining the sequence of the nucleic acid by aligning the base-specifically terminated nucleic acid fragments according to molecular weight.