|dc.description.abstract||The subject of this PhD is the development and testing of a portable membrane
inlet mass spectrometer (MIMS), for the in-situ measurement of volatile organic
compounds (VOCs) in air.
There are several types of VOC monitor available, but few are able to monitor
in-situ with near real-time measurements at concentrations around or lower than
ppm levels. This PhD focuses on the development of the MS-200 and
demonstrates its performance in laboratory and field conditions to analysis a
range of VOCs.
The first chapters of this thesis describe the design considerations that led to the
development of the MS-200. It also discusses the working principles of the
instrument and the laboratory based performance tests that compare the
performance of the MS-200 with the industry standard VOC monitor.
As the MS-200 has sensitivity and detection limits down to ppb levels, it
overcame the limitations of many other instruments, and enabled its use for
many new applications. For example, aromatic and chlorinated hydrocarbons
report detection limits of between 600ppt to 20ppb, other VOCs investigated,
reported detection limits between 20 to 300ppb, low molecular weight alcohols
report detection limits of 0.4 to 6ppm. However, some applications require even
lower detection limits, so an alternative inlet system was developed to increase
the sensitivity but at the expense of the near real-time measurement capability.
Typically the alternative inlet system reduces detection limits by two orders of
magnitudes compared with the standard MS-200.
Subsequent sections of this thesis describe and discuss a range of real world
applications for the MS-200. Most of these investigations were successful,
although a number would need some further work before the MS-200 would be
capable to perform such applications routinely in a commercial environment.
The applications discussed include: Investigations into arson where the
instrument can be used to detect remnants of accelerants used without needing
to return samples to the lab, giving the potential to save both time and money;
Monitoring personal exposure to benzene when refuelling a petrol car, where the
MS-200 demonstrated the advantage of portable real-time monitoring. It was
found that during refuelling the operator could be exposed to benzene
concentrations of a few hundred ppb to 4ppm for a duration of about 3 minutes;
Measuring VOC markers in human breath as a diagnostic tool for cancer and
other illnesses; The use of the MS-200 as an "artificial nose" in the food quality
and flavour analysis.
The thesis discusses the advantages and limitations of this technology as well
as providing a series of recommendations for its future development.||en_US
|dc.publisher||University of Hertfordshire||en_US
|dc.title||Development and application of a portable volatile organic compound analyser||en_US