FIBER OPTIC MODIFIED THERMAL LENS DETECTOR SYSTEM FOR THE DETERMINATION OF AMINO-ACIDS

A novel fiber optic modified thermal lens detector in combination with capillary electrophoresis (CE) is described. The probe and pump laser s used in thermal lensing were adapted via optical fibers to a commerc ial injection and high voltage CE system. The detector performance is demonstrated by monitoring mixtures of derivatised amino acids. Amino acids are labeled with 4-dimethylazobenzene-4-sulfonyl-chloride as abs orbance reagent. Therefore all amino acids possess a large molar absor ptivity in the visible region which because of its stability can be qu alitatively and quantitatively detected with only one excitation line. The miniaturization of the thermal lens detector and the separation o f the excitation and probe laser from the sensor head with optical wav eguides permits combination with typical laboratory CE systems, which generally allow treatment of microliter volumes of amino acids. (C) 19 98 Elsevier Science B.V. All rights reserved.