Measurement of Detector Linearity and Effective Pathlength in Capillary Electrophoresis

Detection linearity and effective pathlength are the two most important parameters for the performance of every photometric detector. Both parameters have been determined experimentally for a high-sensitivity detection cell (HSDC) and an extended light path capillary (ELPC) used in capillary electrophoresis. A series of solutions of increasing sodium chromate concentration was flushed through the capillary under pressure. A plot of sensitivity versus absorbance yielded both the linear range and effective pathlength of the detectors. The upper limit of the linear range was found to be 2190 mAU for the HSDC and 1490 mAU for the ELPC. The effective pathlengths were found to be 1068 and 128 μm, respectively.