Single-color laser-induced fluorescence detection and capillary gel electrophoresis for DNA sequencing

Low zeptomole (1 zmol equals 10-21 mol = 600 molecules) detection limits are produced for DNA sequencing by capillary gel electrophoresis. A 750 (mu) w green helium-neon laser ((lambda) equals 543.5 nm) is used to excite tetramethylrhodamine-labeled DNA fragments in a sheath-flow cuvette. A cooled photomultiplier tube is used to detect fluorescence in a single spectral channel. Sequencing data is generated at a rate of about 70 bases/hour.