Environmental analysis and on-line monitoring: Applications of membrane introduction mass spectrometry
Abstract
Process analysis and environmental analysis are two areas of growing scientific and technological importance. The applicability of membrane introduction mass spectrometric systems utilizing flow-through membrane probes to these applications forms the subject of this thesis. A simple membrane probe interfaced to a commercial quadrupole ion trap detector was used for environmental analysis. This system exhibited fast response times and showed low part-per-billion detection limits for a set of nine organic compounds. Quantitation of well-water samples using the membrane/ion trap system gave agreement with measurements obtained by standard gas chromatographic procedures. These results demonstrate the feasibility of using an ion trap detector interfaced with a membrane probe for water analysis at low levels. A flow injection analysis system was used for on-line monitoring of bioreactors. This system incorporated a sheet direct insertion membrane probe and utilized a triple quadrupole mass spectrometer. Up to fifteen samples of fermentation medium per hour could be quantitated on-line with this system and concentration measurements of liquid-phase products agreed with values measured off-line by gas chromatography. The tandem mass spectrometric capabilities of the triple quadrupole mass spectrometer were used to identify trace metabolites including acetone. The two micro-organisms of interest, Bacillus polymyxa and Klebsiella oxytoca, produce both meso- and R,R-($-$)-2,3-butanediol. Capabilities for isomer distinction were added to the on-line monitoring system by on-line derivatization. 2,3-Buanediol was derivatized using phenyl boric acid to produce a phenyl boric ester which was stable in an aqueous environment and could be used to distinguish the diastereomers. Chemical ionization followed by dissociation of the protonated molecular ions provided the desired isomer distinction. The effects of collision energy and collision pressure were investigated to determine optimal conditions for diastereomer distinction and to gain insight into fragmentation pathways.
Degree
Ph.D.
Advisors
Cooks, Purdue University.
Subject Area
Analytical chemistry
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