The development of a sampling system for general environmental monitoring was the most important aspect of this research programme. Recently, environmental concerns and economical standpoints are ...important issues in considering the analytical processes in various fields such as environmental analysis, toxicological, forensic, clinical drug analysis and many other analytical situations®. In order to achieve environmentally friendly and economical analysis we have thought about the miniaturisation of the analytical methods and instrumentation and this concept has been successfully developed from controlled technologies. The advantage of the miniaturisation is not only for the environmental compatibility but also for the development of high performance analytical systems.This research sought to build and characterise an approach to screening for key volatile organic pollutants in environmental samples. The programme focused on differential mobility spectrometry (DMS) and the background of this detection technology is described and critically evaluated. Arising from these were five experimental aims:• Design and construction of an active membrane sampler concept.. Interfacing of the sampler to various instruments.• Calibrate and commissioning the instruments.• Run preliminary experiments.• Evaluation of the active membrane concept to the well established sampling technique of solid phase micro-extraction.The design and construction of the active membrane sampler, its heating system, construction of interfaces to gas chromatography and differential mobility spectrometry and ancillary experimental systems such as test atmosphere generators are described. Following on from this the results of preliminary tests, a new calibration methodology for ion mobility spectrometry / differential mobility spectrometry systems and testing of the active membrane-differential mobility spectrometry assembly to resolve mixtures are presented. Results generated from the active membrane concept were then compared and evaluated with solid phase micro-extraction sampling technique.The preliminary test results established that the active membrane approach is a simple, and fast sampling technique that incorporates sampling, isolation and enrichment into a single stage. The combination of the sampling approach to a mobility technique has further provided low resource overheads, high sensitivity and controllable selectivity. Sampling times of 1 minute were enough to detect priority pollutants in water at the μg cm-3 level. Increasing the sampling time gave a profound sensitivity on the response and it was possible to saturate a flame ionisation detector at concentrations in the order of ca. 1 μg cm-3 for many of the test compounds. Calibration studies revealed analyte take up has a first order dependency on concentration over a wide dynamic range (dynamic range is the range where an analyst will observe a noticeable change in signal as the concentration changes) and correlation coefficients (an estimate of how well the experimental points fits a straight line) were encouraging.Finally the constructed active membrane-differential mobility spectrometry assembly was found to resolve two components mixtures over a wide range of radio frequency voltage amplitudes. The next phase of the research must necessarily address issues like the membrane geometry and establishing correct identity of compensation voltage assignment.
The development of a sampling system for general environmental monitoring was the most important aspect of this research programme. Recently, environmental concems and economical standpoints are ...important issues in considering the analytical processes in various fields such as environmental analysis, toxicological, forensic, clinical drug analysis and many other analytical situations. In order to achieve environmentally friendly and economical analysis we have thought about the miniaturisation of the analytical methods and instrumentation and this concept has been successfully developed from controlled technologies. The advantage of the miniaturisation is not only for the environmental compatibility but also for the development of high performance analytical systems.
