A novel, portable, filter fluorometer was developed for the determination of
chloroform and TCE at environmentally-relevant levels when coupled with improved
sampling techniques and reagents. Reagents selective for the TCE or chloroform
convert these toxic species into fluorescent species that can be monitored. The
fluorometer is based on LED excitation light sources, a battery-operated
photomultiplier tube as a radiation detector, and appropriate excitation and emission
filters. A unique low-power, miniature heater inside the cell holder of the fluorometer
provides control of the temperature of the reagent solution above ambient temperature.
The fluorometer and the sampling systems, including a miniature air pump, are
portable and can be operated from a small lead battery over an entire day.
Sparging, passive transfer, and membrane sampling techniques were used to
transfer TCE or chloroform from the sample solution as a vapor into the appropriate
reagent and to provide preconcentration. The apparatus for membrane sampling was
improved to be applicable for continuous sampling of water in the field situations with
minimal sample manipulation. Each of the three sampling techniques provides a
transfer rate of the analyte of ~1 ng/min per ng/mL of analyte in the sample.
The optimized reagent based on 1-(3-pyridylmethyl)urea provides high
selectivity to chloroform and the reagent based on isonicotinamide has excellent
selectivity to TCE. These two reagents serve as an alternative to the more common
pyridine reagent for the determination of chloroform or TCE in water and eliminate
the exposure of the user to toxic pyridine vapor.
The developed filter fluorometer, the optimized reagents, and the membrane
sampling technique provide a detection limit for chloroform of 0.2 and 10 ng/mL,
respectively, with the pyridine and 1-(3-pyridylmethyl)urea reagent. The detection
limit for TCE is 0.3 ng/mL with the isonicotinamide reagent. For TCE, the detection
limit is almost two orders of magnitude better than obtained previously with a
fluorometric technique. Analysis times vary from 15 to 30 min. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30845 |
| Date | 24 April 2003 |
| Creators | Prayoonpokarach, Sanchai |
| Contributors | Ingle, James D. Jr |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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