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Proceedings Paper

Ground Water Monitoring Using Laser Fluorescence And Fiber Optics
Author(s): Wayne Chudyk; Kenneth Pohlig; Nicola Rico; Gregory Johnson
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Paper Abstract

In-situ measurement of aromatic ground water contaminants, including the benzene, ethylbenzene, toluene, and xylenes (BTEX) fraction of gasoline, has been demonstrated using fiber optic systems. A prototype field instrument has shown that this method has advantages over traditional sampling and analysis. Problems encountered and solved include coupling of the laser energy into to fiber, sensor design, and detector configuration to optimize instrument sensitivity. The effects of sensor length, corresponding to well depth, on limits of detection are presented. Effects of potential interferences, including external fluorescence quenchers, are discuss-ed. The resolution of complex mixtures is addressed, with modifications to the detector shown to be effective in separation of groups of contaminants. Instrument design considerations include the need for portability, ruggedness at field sites, and ease of operation. The modular instrument design used is shown to help solve these potential problems, while maintaining analytical sensitivity and reproducibility. Modular optical system design has also shown to be useful when modifications are made. Changes in the detector as well as provisions for multiple laser sources have allowed a flexible system to be configured to meet analytical demands as they arise. Sensor design considerations included high ultraviolet transmission, physical flexibility, resistance to breakage, and resistance to chemical and/or biological fouling. The approach to these problem areas is presented, as well as discussion of the methods used to minimize effects of fiber solarization. Results of testing the field portable prototype are presented for a variety of typical ground water analysis sites, illustrating the usefulness of this new technology in environmental monitoring.

Paper Details

Date Published: 19 January 1989
PDF: 4 pages
Proc. SPIE 0990, Chemical, Biochemical, and Environmental Applications of Fibers, (19 January 1989); doi: 10.1117/12.959972
Show Author Affiliations
Wayne Chudyk, Tufts University (United States)
Kenneth Pohlig, Tufts University (United States)
Nicola Rico, Tufts University (United States)
Gregory Johnson, Tufts University (United States)

Published in SPIE Proceedings Vol. 0990:
Chemical, Biochemical, and Environmental Applications of Fibers
Robert A. Lieberman; Marek T. Wlodarczyk, Editor(s)

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