PHOTOTHERMAL EFFECTS IN A CAPILLARY AND OPTIMUM CONDITIONS FOR ABSORBENCY DETECTION OF CAPILLARY ELECTROPHORESIS

Highly sensitive detection for capillary electrophoresis was made possible using the mechanical vibration of a capillary induced by intensity-modulated laser irradiation, However, other photothermal effects, such as the thermooptical effect and the photothermal beam deflection effect, were also induced, In certain geometrical configurations, these effects caused a very high background and prevented quantitative detection. The dominant effect and the optimum configuration were determined by scanning a probe beam along the capillary, To avoid the influence of the heat generated from the glass part of the capillary tube, which cannot be neglected in such a weak absorbance detection, it was found that the probe beam should pass outside of the thermal diffusion region of the glass, where the capillary vibration induced by laser effect was dominant. Under this condition, 8 amol of four DABSYL amino acids was detected.