Issue 10, 1997

On-column Indirect Photothermal Interference Detection for Capillary Zone Electrophoresis

Abstract

An indirect photothermal interference detection method, which is based on the diffraction of a probe laser beam by a capillary tube, for detecting metal cations separated by capillary zone electrophoresis (CZE) is described. In this capillary photothermal interference detector, a 2 mW He–Ne probe laser is employed to provide the probe beam and an 18 mW He–Ne pump laser is used to supply the pump beam. Factors that contribute to the noise and signal in indirect photothermal interference detection in CZE, such as the noise from the scattered light caused by both the probe beam and the pump laser beam, and effects of the concentration of ethanol and NaCl on the separation efficiency, were studied. The effect of scattered light can be reduced effectively with the configuration constraints investigated for photothermal capillary absorption measurements. With Methylene Blue added to carrier electrolyte as an absorber, three typical metal cations (KI, CuII and AlIII) were separated using this system. For CuII, a 2.1 × 107 mol l1 concentration detection limit (S/N = 2) without preconcentration and a 1.02 × 1017 mol detection limit as absolute amount were measured, considering the optical sampling volume estimated to be 50 pl, and 1.99 × 106 theoretical plates were observed on the laboratory-made CE system. It was demonstrated that indirect photothermal interference detection is suitable for small capillaries and a large ionic strength range for CE analysis.

Article information

Article type
Paper

Analyst, 1997,122, 1089-1093

On-column Indirect Photothermal Interference Detection for Capillary Zone Electrophoresis

Y. Hu, J. Cheng, Y. Deng and Y. Hu, Analyst, 1997, 122, 1089 DOI: 10.1039/A700119C

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