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Proceedings Paper

Double-beam thermal lens as detector system for capillary electrophoresis
Author(s): Bernd S. Seidel; Elke Steinle; Werner N. Faubel; Hans-Joachim Ache
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Paper Abstract

The properties and performances of the thermal lens detector, based on a double beam absorption scheme, were studied in a capillary electrophoresis system with different types of pollutants, e.g. pesticides. The setup of the detector system is miniaturized using smallest deflection pathlengths between the cell and the pinhole (5 mm). The probe laser beam (HeNe laser, 633 nm) and the excitation beam (Ar+ ion laser, 364 nm, 457 nm, 488 nm, 514 nm) with a crossed setup are directed by mirrors into two microscope objectives, which focused the beam to a 15 micrometer waist inside the capillary. The detection volume is in the range of 75 n1 using a 75 micrometer capillary. The change of the intensity of the probe beam is detected behind a pinhole with a photodiode, which is protected with different band pass interference filters. The excitation laser can be used in the multiline order. Different types of hydrodynamic and electrokinetic probe injections are compared to optimize the probe volume. Micellar electrokinetic methods are used for separation of pesticides. The performance of the detector in capillary electrophoresis was assessed by different types of capillaries and compared with a conventional absorption detector. The limit of detection is at least one order of magnitude better than the absorption detector.

Paper Details

Date Published: 10 December 1996
PDF: 10 pages
Proc. SPIE 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII, (10 December 1996); doi: 10.1117/12.260603
Show Author Affiliations
Bernd S. Seidel, Forschungszentrum Karlsruhe (Germany)
Elke Steinle, Forschungszentrum Karlsruhe (Germany)
Werner N. Faubel, Forschungszentrum Karlsruhe (Germany)
Hans-Joachim Ache, Forschungszentrum Karlsruhe (Germany)

Published in SPIE Proceedings Vol. 2836:
Chemical, Biochemical, and Environmental Fiber Sensors VIII
Robert A. Lieberman, Editor(s)

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