Premium
A multireflection cell for enhanced absorbance detection in microchip‐based capillary electrophoresis devices
Author(s) -
SalimiMoosavi Hossein,
Jiang Yutao,
Lester Lianne,
McKin Graham,
Harrison D. Jed
Publication year - 2000
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/(sici)1522-2683(20000401)21:7<1291::aid-elps1291>3.0.co;2-5
Subject(s) - absorbance , stray light , optics , materials science , optical path length , capillary electrophoresis , optical path , microfluidics , calibration , capillary action , detector , analytical chemistry (journal) , optoelectronics , chemistry , nanotechnology , chromatography , physics , quantum mechanics , composite material
The design, fabrication and testing of a photolithographically fabricated, glass‐based multireflection absorbance cell for microfluidic devices, in particular microchip‐based capillary electrophoresis (CE) systems is described. A multireflection cell was fabricated lithographically using a three‐mask process to pattern aluminum mirrors above and below a flow channel in a chip, with 30 μm diameter optical entrance or exit apertures (one in each mirror) positioned 200 μm apart. Source and detector were positioned on opposite sides, and the metal mirrors were made 1 cm square, to reduce stray light effects. Calibration curves using bromothymol blue (BTB) with a 633 nm source (He:Ne laser) were linear to at least 0.5 absorbance units, with typical r 2 values of 0.9997, relative standard deviations in the slopes of ± 1.3%, and intercepts of zero within experimental error. Effective optical pathlengths of 50—272 μm were achieved, compared to single‐pass pathlengths of 10—30 μm, corresponding to sensitivity enhancements ( i.e. , optical path length increase) of 5 to 10‐fold over single‐pass devices. Baseline absorbance noise varied within a factor of two in almost all devices, depending only weakly on path length. This device can give much higher absorbance sensitivity, and should be much easier to manufacture than planar, glass‐based devices previously reported.