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Significant improvement of signal‐to‐noise ratio in capillary electrophoresis through optimization of aperture width for UV absorption detection
Author(s) -
Kitagishi Keiko,
Sato Yasuhiro
Publication year - 2001
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200109)22:16<3395::aid-elps3395>3.0.co;2-g
Subject(s) - capillary action , optics , capillary electrophoresis , absorbance , ray , materials science , light intensity , absorption (acoustics) , signal (programming language) , lens (geology) , path length , optical path , aperture (computer memory) , light scattering , molar absorptivity , chemistry , physics , scattering , chromatography , computer science , acoustics , composite material , programming language
In capillary electrophoresis (CE), light flux passes through a capillary cell and is in most cases detected photometrically. Due to the thinness of the cell, a part of the light passes through the wall and misses hitting the sample. In most CE apparatuses, incident light is focused by converging lenses in order to condense light beams passing through the capillary. Considering the aberration of lenses and lens effects of capillary, we assumed that light beams inside were approximately parallel. Although the path lengths of light beams vary depending on their tracks, we could estimate the virtual light path length, L , by measuring absorbance when concentration and molar absorptivity of the sample solution were known. A light‐restricting device consisting of narrow slits makes effectively L longer and signal intensity higher. On the other hand, noise increases as light width narrows. The signal‐to‐noise ratio showed a maximum at 68 νm of light width for a capillary with diameter of 75 νm. The optimized L was evaluated by the simulation. The experimental data verified it even in indirect UV detection. Our approach could help to design the optics of CE apparatuses.