ABSTRACT
Separations of small solutes and macromolecules by capillary electrophoresis (CE) have been widely accepted by the scientific community, mainly due to its inherent advantages such as high resolution, compatibility with smaller samples, consumption of less buffer, rapidity, and ease of automation. Some of these advantages stem from the use of capillaries with inner diameters of 1-100 µm. With such small diameters, injection volumes are typically 0.1-10 nL, leading to a difficulty of detection. For detecting an analyte present at 1 nM concentration, with a 0.1-nL injection volume, extremely sensitive detection systems, providing a detection limit below 100 zmol for the analyte, are needed. Over the past 20 years, a number of nanoscale detectors, based on mass spectrometry, amperometry, chemiluminescence, raidochemistry, and fluorescence, have been developed to meet the extraordinary sensitivity challenges posed by CE. Of these, laser-induced fluorescence (LIF) has been the most successful and has been applied to single-cell analysis, DNA sequencing and separations, protein analysis, single-molecule detection, etc. One good example is that LIF, in conjunction with capillary array electrophoresis (CAE), has been successfully used for DNA sequencing, which has considerably assisted in the rapid progress of the Human Genome Project.
