Browsing by Author "Lai, Ching Kwan"

Gas chromatography is considered to be a powerful tool for studying a wide range of phys-icochemical parameters. Gas chromatography is able to separate components from a mixture and determine the physicochemical properties simultaneously; only simple modifications of the gas chromatographic instrument is required for various measurement conditions, and the advances in technology has improved the gas chromatographic hardware for measurement. However, the analysis of aerosols or other complex samples requires excellent separation efficiency, which may not be achieved by a single chromatographic technique alone. Therefore, comprehensive two-dimensional gas chromatography is a very powerful separation technique that can be used for complex samples. The focus of this thesis was the measurement of physicochemical parameters using gas chromatographic techniques. The experimental part focused on the development of a new method for simultaneous determination of vapor pressures for several compounds in complex matrices. The main aim was to develop a technique for utilization of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry in order to study unknown compounds with similar structures from aerosol sample. In addition, several approaches for the vapor pressure determination were studied for some environmentally important compounds. The development of the measurement technique included isothermal and temperature-programmed gas chromatography with different polar and derivatized homologous series as reference. The new technique for vapor pressure determination using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry was successfully developed. It is a simple, rapid and versatile method that can be used to analyze other complex samples without extensive sample pretreatment. Inverse gas chromatography has become a powerful technique in evaluating properties of materials, including their physicochemical properties. However, this thesis focused on the potential of other gas chromatographic techniques such as those utilizing Kováts' retention indices, headspace-gas chromatography techniques and the gas-stripping method to measure some selected thermodynamic parameters. The basic fundamental theories of the methods, experimental practices and their applications were described.