A novel refractive-index detection scheme used for capillary electrophoresis detection, based on the interference of two retroreflected beams from the outer surface of a capillary tube illuminated by a focused laser beam, is described. A theoretical description and experimental measurement of the intensity profile of the interference fringe pattern in the detection plane are presented. The factors that limit the sensitivity of the proposed refractive-index detection scheme are discussed and compared with the transmitted beam interference and backscatter-based refractive-index detection configurations. The proposed refractive-index detector was used successfully for detection of capillary electrophoresis separations of saccharose, maltose, and lactose with a capillary tube of 50-μm inner diameter and a simple experimental setup.
© 1998 Optical Society of America
Original Manuscript: September 17, 1997
Published: February 20, 1998
Yanzhuo Deng and Bincheng Li, "On-column refractive-index detection based on retroreflected beam interference for capillary electrophoresis," Appl. Opt. 37, 998-1005 (1998)