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Journal of Biomedical Optics

Thermal lens detector system for capillary electrophoresis
Author(s): Bernd S. Seidel; Werner N. Faubel; Hans-Joachim Ache
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Paper Abstract

The characteristics and the performance of a thermal lens detector, which uses a double-beam absorption scheme, were studied in a capillary electrophoresis system with various types of toxic pollutants, e.g., pesticides. The setup of the detector system was miniaturized using the smallest diverging path lengths between the cell and the pinhole (4 mm). The probe laser beam (He:Ne laser, 633 nm) and the excitation beam (Ar+ ion laser, 364, 457, 488, and 514 nm) with a crossed setup were directed by mirrors into two microscope objectives that focused the beam to a 5-μm waist inside the capillary. The detection volume was on the order of 75 nl when a 75-μm capillary was employed. The change in intensity of the probe beam was detected by a photodiode behind a pinhole, which was protected with different band-pass interference filters. The excitation laser can be used in the multiline order. Micellar electrokinetic methods are used for pesticide separation. The performance of the detector in capillary electrophoresis was assessed with various types of capillaries and compared with a conventional absorption detector. The limit of detection is at least one order of magnitude better than it is with the absorption detector.

Paper Details

Date Published: 1 July 1997
PDF: 6 pages
J. Biomed. Opt. 2(3) doi: 10.1117/12.275450
Published in: Journal of Biomedical Optics Volume 2, Issue 3
Show Author Affiliations
Bernd S. Seidel, Forschungszentrum Karlsruhe (Germany)
Werner N. Faubel, Forschungszentrum Karlsruhe (Germany)
Hans-Joachim Ache, Forschungszentrum Karlsruhe (Germany)


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