Miniaturized thermal lens device for capillary electrophoresis.

In this paper we will report on the combination of a miniaturized fiber optic modified photothermal sensor (size 2 x 2 x 2 cm) to capillary electrophoresis (CE) as detection device. The properties and the performances of the thermal lens detector, based on a double beam absorption scheme, were studied in a capillary electrophoresis system with different types of toxic pollutants, e.g. pesticides. A tunable Argon ion laser, which emits between 364 and 514 nm, was adapted to a commercial injection and high voltage CE system. The miniaturization of the thermal lens detector head with optical waveguides allows the combination with typical CE systems, therefore pesticides in microliter volumes can be treated. The detector performance is demonstrated with the monitoring of pesticides in capillaries with various diameter. The limit of detection is one of two orders of magnitude better than conventional absorption detector.