EXTENDED PATH-LENGTH POSTCOLUMN FLOW CELL FOR UV-VISIBLE ABSORBENCY DETECTION IN CAPILLARY ELECTROPHORESIS

Abstract

A new type of post-column flow cell with extended optical path length has been developed to improve sensitivity of UV-visible absorbance detection for capillary electrophoresis. In this flow cell, the outlet of the capillary column is connected vertically to the middle of a 3-mm microchannel. Auxiliary flows are employed to flush substances eluted from the outlets of the microchannel. The optical path length is the full length of the microchannel. An 8-fold signal-to-noise ratio improvement over on-column detection has been demonstrated. However, the postcolumn flow cell suffered 44% loss in resolution. A limit of detection of 3.2 10(-7) M has been obtained for fluorescein isothiocyanate.