Time- and wavelength-resolved spectroscopic methods and their applications for chemical speciation.

摘要

Qualitative and quantitative chemical speciation in a given sample can be difficult. Currently, many different methods are available for chemical speciation, including chromatographic techniques as well as highly specific sensors and probes. This dissertation will discuss the application of wavelength- and time-resolved spectroscopic techniques in capillary electrophoresis and in fiber optic sensors.;An in-column, wavelength-resolved optical detection method for capillary zone electrophoresis (CZE) will also be discussed. Wavelength-resolved CZE separation of rhodamine dyes was successfully carried out in a capillary with a fiber optic cable inserted to the edge of the observation window. The fiber optic was used to transmit laser radiation, which served as the excitation source for fluorescence spectroscopy. Detection limits in the picomole range were obtained for rhodamine 590 and kiton red.;Time-resolved CZE separations of protein conjugates were also done using the in-column method of detection. The fluorescence emission of the analytes was monitored for a given time after the Q-switch of the laser. This allowed delayed monitoring of the fluorescence emission. CZE analysis of commercial proteins conjugated to rhodamine indicates the samples contain a heterogeneous mixture of conjugates, possibly with different ratios of label to protein. Detection limits in the femtomole range were obtained for rhodamine 590.;The number of sensors based on fiber optics continues to increase but only a few are available for determination of anions. The development of a fiber optic probe for iodide based on the enzyme lactoperoxidase (LPO) will be described. Detection limits of 0.2 mM and 0.1 mM iodide were obtained. The natural selectivity of this enzyme leads to a sensitive probe with no interferences from other halides.