Miniaturization of batch- and flow-type chemiluminescence detectors in capillary electrophoresis

Glass and PTFE tubes as detection cells were put in small light-tight boxes to achieve miniaturization of batch- and flow-type chemiluminescence detectors for capillary electrophoresis. These light-tight boxes which included a detection cell and a photosensor module were successfully designed. In the batch-type detector using a glass tube as a detection cell, the influences of a repeated injection of sample and a reagent volume of the detection cell on chemiluminescence intensity were examined in detail. By using 3.8 mm I.D. glass tube including 400 μl chemiluminescence reagent solution, the chemiluminescence peaks were reproducibly observed for the repeated injection experiment up to the eight injection with each run time of 3.0 min. Dansyl-Trp was determined over the range 3·10−8–1·10−5 M with the detection limit of 0.43 fmol (S/N=3). In the flow-type detector using a PTFE tube as a detection cell, both ends of the PTFE tube were connected to three-way joints; a chemiluminescence reagent solution was delivered into the cell and a capillary was inserted through one of the joints while an electrode was inserted through the other one. Dansyl-Trp was determined over the range 1·10−7–1·10−5 M with the detection limit of 1.3 fmol (S/N=3). By using the compact flow-type detector, a mixture of dansyl-amino acids was separated and detected in micellar electrokinetic chromatography mode.