Miniaturized thermal lens device for capillary electrophoresis

Abstract

In this paper we will report on the combination of a miniaturized fiber optic modified photothermal sensor (size 2 × 2× 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. © 1998 John Wiley & Sons, Ltd.

Sensitivity Enhancement in Near-Field Photothermal-Lens Detection in Capillary Electrophoresis Using Laser-Induced Online Precipitation

“…4, is 0.5 lM, which is below the values previously reported for thermal-lens detection in CZE under similar detection condi- tions. 4,6,7,12,14,18,19 The detection limit for the ''central'' configuration and for the conventional UV-Vis detection scheme is 6 lM. Thus, the ratio between detection limits achieved for ''marginal'' and ''central'' configurations is in perfect agreement with the sensitivity enhancement calculated in the previous section.…”

“…5); the increase in the sensitivity (Table I) is in accordance with the expected value. 12 Thermal-lens detection of the 4-aminoazobenzene zone passing through the detection window results in a peak of an unusual shape compared to that obtained by UV-Vis detection (compare Figs. 4E and 4F).…”

“…1), a schematic proved advantageous for photothermal detection in combination with capillary electrophoresis. 12,22,23 For the excitation, a He-Cd laser is used (excitation wavelength, k e , 325 nm, IK3552R-G Kimmon Electronic Co., Ltd. Tokyo, Japan). The laser power in the sample P e is 50 mW, and spot size at the waist is 7.7 lm.…”

“…Crossed-beam photothermal-lens (thermal-lens) spectrometry (TLS) 1,2 is a reliable and sensitive detection technique for stateof-the-art capillary zone electrophoresis (CZE) [3][4][5][6][7][8][9][10][11][12] and has many applications. 6,[10][11][12][13][14][15][16][17] It provides a drastic increase in sensitivity compared to the conventional ultraviolet-visible (UV-Vis) detection for various analytes.…”

Thermal Lens Spectrometric Detection in Flow Injection Analysis and Separation Techniques

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