Capillary zone electrophoresis separation and laser-induced fluorescence detection of zeptomole quantities of fluorescein thiohydantoin derivatives of amino acids

Capillary zone electrophoresis, when combined with laser-induced fluorescence, is a very powerful technique for the separation and determination of minute amounts of labeled amino acids. This paper presents the determination of the fluorescein thiohydantoin derivative of 17 amino acids which takes 13.5 min. The detector, based on laser-induced fluorescence, is optimized with respect to laser power to produce detection limits, three standard deviations above background, ranging from 1 to 2 zeptomoles (1 zeptomole = 1 zmole = 10(-21) = 600 analyte molecules) injected onto the capillary.