ON-COLUMN REFRACTIVE-INDEX DETECTION BASED ON RETROREFLECTED BEAM INTERFERENCE FOR CAPILLARY ELECTROPHORESIS

A novel refractive-index detection scheme used for capillary electroph oresis detection, based on the interference of two retroreflected beam s from the outer surface of a capillary tube illuminated by a focused laser beam, is described. A theoretical description and experimental m easurement of the intensity profile of the interference fringe pattern in the detection plane are presented. The factors that limit the sens itivity of the proposed refractive-index detection scheme are discusse d and compared with the transmitted beam interference and backscatter- based refractive-index detection configurations. The proposed refracti ve-index detector was used successfully for detection of capillary ele ctrophoresis separations of saccharose, maltose, and lactose with a ca pillary tube of 50-mu m inner diameter and a simple experimental setup . (C) 1998 Optical Society of America.