Capillary electrophoresis (CE) has been shown to be a powerful and efficient analytical separation technique. The development of sensitive detection methods has become one of the most important subjects in CE studies. Absorption and fluorescence detections are commonly used as on-column optical detection modes, due to an extremely small sample zone and the capillary inner diameter in CE. More sensitive detection can be realized when the analytes can be used in conjunction with laser-induced fluorescence, 1 amperometric, 2 or radiometric 3 detection. An alternative sensitive detection uses chemiluminescence (CL). 4 A CL detection system combined with separation methods can offer excellent analytical selectivity and sensitivity. CL has already been shown to be a highly sensitive detection method in both FIA and HPLC. [5][6][7] Recently, the applicability of CL detection in CE has been successfully demonstrated.Various CL reagents, such as luminol, 8,9 acridinium, 10 peroxyoxalate, 11,12 and Ru(II) complex, 13 have been utilized. We have also reported various types of CE with CL detectors, including batch-type 14-16 and the flow-type CL detectors. 8,11,17 CL detection featured a high sensitivity, a wide determinable range of the sample concentration, and an inexpensive apparatus and reagent.Additionally, a miniaturization of the analytical system must be a predominant merit in a CL detector, because it does not need any light source or spectroscpopy. We could combine microchip CE with a CL detector 18,19 based on the concept of a µ-total analytical system. However, when one takes notice of the separation modes in a CE with CL detector, capillary zone electrophoresis has been used in almost all studies. Only micellar electrokinetic chromatography and capillary isoelectric focusing have been applied as other separation modes in several studies. 20,21 Therefore, although CE with CL detection methods has shown high sensitivity, the methods were not always satisfactory for the separation ability in CE. Capillary gel electrophoresis (CGE) has been recognized as an effective method for the analysis of biopolymers, such as proteins, saccharides, and nucleic acids. A migration buffer solution containing a polymer as the separation medium is also useful and effective, when compared with that using a crosslinked gel immobilized on the inner wall of the capillary. [22][23][24][25] The buffer solution containing the polymer can be easily replaced in the capillary, leading to a reproducible separation of analytes. A separation mode with a buffer solution containing carboxymethylcellulose (CMC) was developed to analyze DNA fragments. 26 We tried for the first time to combine a separation mode using a polymer solution with a CL detector for the analysis of biopolymers. CMC was used as the separation medium. Two post-column CL detectors of batch-and flow-types, both of which were originally developed in the authors' laboratory, were examined. The flow-type CL detector was found to show better resolution than the batch-type for a se...

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