NOISE AND DETECTION LIMITS OF INDIRECT ABSORPTION DETECTION IN CAPILLARY ZONE ELECTROPHORESIS

The factors which contribute to the noise and signal in indirect absorption detection in capillary zone electrophoresis are studied. Two independent noise sources, the visualization agent and the detector, are distinguished. The noise from the visualization agent can be affected by the applied voltage, the surface modification of capillaries and the concentration of the visualization agent. A new factor named the "noise coefficient" is found which represents the contribution to the noise from the visualization agent. The physical interpretation of the noise coefficient is the ratio of the concentration fluctuation to the concentration of the visualization agent. A new equation that correlates detection limits with molar absorptivity and concentration of the visualization agent, noise coefficient and instrument noise is proposed, and the functions of those factors are discussed.