Evaluation of a separation-based fiber-optic sensor for process analysis

A novel separation-based fiber-optic sensor (SBFOS) with potential for industrial process and waste analyses is described. The SBFOS is a chemical monitor that integrates the separation selectivity afforded by capillary electrophoresis with the remote and high sensitivity capabilities of laser-induced fluorescence and fiber-optic sensing. A small streamlined sensor is fabricated by mating a short separation capillary to laser-excitation and emission-collection fibers in a low-volume cross. Separations are performed in a zonal mode by injecting discrete volumes of sample from a contained flowing stream using a compatible sampling device. The implementation of this configuration for performing process analytical chemistry is discussed and illustrated. Two classes of analytes-metal cations and aminopolycarboxylate ligands-are monitored based on the formation of fluorescent complexes with 8-hydroxyquinoline-5-sulfonic acid: which is added on-line without contaminating the sample stream. The observed analytical figures of merit include relative standard deviations of 4.8% and 2.7% for peak intensity and migration time (Mg2+), respectively, efficiencies of approximately 10(4) theoretical plates. and metal and ligand limits of detection in the parts per billion range. (C) 1999 John Wiley & Sons, Inc.