Light-based detection methods for capillary electrophoresis

The small sample volumes used in capillary electrophoresis (CE) make the technique suitable for myriad small-scale biochemical and materials science applications. These small volumes also require detection methods that exhibit high sensitivity and suitable selectivity. Such rigorous demands on detector performance can have important consequences with respect to other aspects of the CE system. For example, it is well known that higher efficiency and faster separations are achieved using smaller inner diameter (ID) capillaries. And yet 50-µm ID capillaries are more common than 5-µm ID capillaries in systems using light-based detection, primarily because the longer optical path length of the larger capillary aids in detection. In this way, the performance of the detection system can dictate the overall performance of a given CE system. Thus, knowledge of the various detection modes available, as well as their respective figures of merit, aids in designing CE-based methods of analysis (see Table 9.1).¹.