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Lariat crown ethers and Chinese herb medicines are the two areas investigated in this thesis. Selectivity of the lariat crown ethers toward metal ions can be estimated easily with ESI-MS. All sym-dibenzo-16-crown-5 ethers 2a ~ 2g have been shown to be most selective toward Li+ among alkali metal ions in pure methanoi. When water is introduced, the influences on selectivity will be controlled by the nature of theirrespective side arms. The selectivity toward Na+ will increase when its side arm is hydrophilic and the steric hindrance is small; and the selectivity is favor to Li+ still when its side arm is hydrophobic and the steric hindrance is large.
Selectivity of lariat crown ethers towarrd Li+, Na- and K+ also changes with different counter anions. Nitrates give the best Na+ selectivity; and the ratio R, IcNa+/IcLi+, is RNo3 > RCl > RBr. It appears that heats of formation of the used salts are the important parameter in controlling the selectivies of these lariat crown ethers toward alkali cations.
Externally added cation such as Rb- or Cs- will affect the selectivity of lariat crown ethers toward Na+ and Li+ due to the ligating interaction with donor atoms of the side arm. The influence of Cs+ is larger than that of Rb+, and the steric hindrance of the side arm is a more important parameter in controlling selectivity than the percentage of water in the solvent system.
Calibration for relative cationization efficiencies of the meltallated crowns [Crown+M]+ have been shown to be essential for comparison of selectivity in ligand metal interactions. By using the peak intensities which have been corrected by the relative cationization efficiencies S, an easy and fast method for determination of the stability constants of different metal ion complexes with crown and lariat crown ethers using ESI-MS has been developed. With this kind of calibration, concentration of the metal ion can also be calculated directly by measuring their respective peak intensities.
Combination of ESI/MS and ESI/MS/MS is useful for structural elucidation of some protoberberine alkaloids from Coptidis Rhizoma. Important fragmentation pathways have been proven by tandem mass techniques. Using the diagnostic fragments, the major contents in the Phellidendri Cortex (rutaceous plant) have been identified as berberine and palmatine; and their concentrations have been estimated as 6.4 x 10-3 M and 3.2 x 10-3 M, respectively in the crude extract.
4α-Methylergosta-8,24(28)-dien-3,7,11-trion-26-oic acid and 4α-methylergosta-8,24(28)-dien-3,11-dion-7β-ol-26-oic acid are two clinically active components found in Antrodia cinnamomea. Using the specific fragmentation in their mass spectra together with the ratio of these diagnostic ions in their respective SIM mass spectra, and/or their MS/MS spectra, a fast, simple, and efficient mass spectral method has been developed for identification of these compounds in Antrodia cinnamomea preparations without prior isolation of the individual compound.
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