Date of Award

1981

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Methods for the determination of personal exposure to chlorine, hydrogen sulfide and hydrogen cyanide have been devised. Samples are collected by permeation through a silicone membrane into 10 mL of an absorbing reagent. For the chlorine monitor, samples are collected in a fluorescein-bromide reagent. The resulting eosin is measured spectrophotometrically and the Cl(,2) exposure is calculated. The detection limit of the method is 0.013 ppm Cl(,2) for an 8 h exposure period with a working range of 0.1-2.0 ppm. The device responds in less than one minute and is unaffected by variations of temperature and humidity. Response of the device is pH dependent and is optimized by buffering the reagent at pH 7.0. No significant interferences are encountered, but the solution fades if exposed to intense sunlight for extended periods. The hydrogen sulfide monitor collects samples in 0.2N NaOH containing EDTA and the resulting sulfide is analyzed by the methylene blue method. The detection limit for an 8 h exposure is 0.01 ppm H(,2)S with a working range of 0.1-20 ppm. The device responds in less than 30 sec and is unaffected by variations in temperature and humidity. The use of EDTA increases sample stability as to allow sampling of over one week. The only significant interference observed is from chlorine (-6.6%). For the hydrogen cyanide monitor, samples are collected in 0.1N NaOH and analyzed by conversion to a colored species. The detection limit for the method is 0.01 ppm HCN for an 8 h exposure with a working range of 0.1-50 ppm. The device responds rapidly and is unaffected by humidity. Temperature affects the response wth a maximum error of (+OR-) 5% over the nomal working range (0-45(DEGREES)C). The only significant interferences observed were from chlorine and cyanogen (-73.7 and +21% relative error, respectively). The effects of the former were reduced to less than -3% with the addition of ascorbic acid to the absorbing solution. In all cases, a device can be constructed that is small in weight and size and can serve as either an area or personal monitoring system.

Pages

108

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