Doctoral Dissertations


Mark Gehrke


"Civilian populations in many parts of the world are threatened by hidden land mines. Detection of the concealed land mines is a challenging task. It is estimated that with current technologies it would require over 1,100 years to remove the 110 million mines presently deployed. New detection techniques need to be not only less prone to produce false alarms but faster and cost effective.

Chemical vapor sensors are inherently less likely to produce false alarms than the currently used metal detection devices. Chemical vapor sensors produce a signal for nitroaromatic vapors in the airspace above a buried mine which emanate from the mine's explosive. The present study was undertaken to investigate rapid air sampling and enrichment techniques and to study the application of electron attachment reactions for improving the selective determination of nitroaromatic explosives.

Rapid air sampling and enrichment was carried out by collecting the sample within a low volume capillary column cold spot at high sampling rates. Two air sampling devices, supported by sampling efficiency studies, were designed and evaluated. An automated cryogenic sampling concentrator device made use of a concentric capillary arrangement and passivated sampling conduits. The concentric arrangement permitted high vacuum drawn sampling rates and a very low trap volume. A second device collected the sample into a moveable sample trap which was cooled using a thermoelectric cold plate arrangment. The cold plate sampler was capable of discriminating between the target explosives and volatile contaminants.

Selective detection of nitroaromatic explosives was carried out through the application of electron attachment reactions. Electron attachment reaction studies showed that unlike chlorinated analyte, nitroaromatics are destroyed by an electron attachment reaction and do not lead to discernible products. Polychlorinated aromatics lead to discernible hydrodechlorination products. A low-volume, tandem electron capture detector (ECD) electron attachment reactor apparatus was designed to demonstrate discriminate monitoring of electronegative volatile and semivolatile organics. The electron attachment reaction differences were used to successfully discern between nitroarmatics and polychlorinated analyte based upon differences in the response of an ECD placed before an electron attachment reaction reactor and the response in an ECD placed directly after the reactor"--Abstract, pages iii-iv.


Kapila, Shubhender

Committee Member(s)

Whitefield, Philip D.
Armstrong, Daniel W., 1949-
Sotiriou-Leventis, Lia
Hagen, Donald E.



Degree Name

Ph. D. in Chemistry


University of Missouri--Rolla

Publication Date

Spring 2000


x, 127 pages

Note about bibliography

Includes bibliographical references (pages 117-126).


© 2000 Mark A. Gehrke, All rights reserved.

Document Type

Dissertation - Restricted Access

File Type




Thesis Number

T 7762

Print OCLC #


Electronic OCLC #


Link to Catalog Record

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