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Fundamentals and practice for ultrasensitive laser‐induced fluorescence detection in microanalytical systems
Author(s) -
Johnson Mitchell E.,
Landers James P.
Publication year - 2004
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200406086
Subject(s) - capillary electrophoresis , capillary action , detection limit , laser induced fluorescence , detector , fluorescence , laser , sensitivity (control systems) , materials science , chemistry , nanotechnology , chromatography , analytical chemistry (journal) , optics , physics , electronic engineering , composite material , engineering
Laser‐induced fluorescence is an extremely sensitive method for detection in chemical separations. In addition, it is well‐suited to detection in small volumes, and as such is widely used for capillary electrophoresis and microchip‐based separations. This review explores the detailed instrumental conditions required for sub‐zeptomole, sub‐picomolar detection limits. The key to achieving the best sensitivity is to use an excitation and emission volume that is matched to the separation system and that, simultaneously, will keep scattering and luminescence background to a minimum. We discuss how this is accomplished with confocal detection, 90° on‐capillary detection, and sheath‐flow detection. It is shown that each of these methods have their advantages and disadvantages, but that all can be used to produce extremely sensitive detectors for capillary‐ or microchip‐based separations. Analysis of these capabilities allows prediction of the optimal means of achieving ultrasensitive detection on microchips.