Development of New Separation Analysis and Continuous Flow Analysis Using Supercritical Water or Subcritical Water

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A chromatograph using supercritical water or subcritical water as mobile phase was constructed and its separation characteristics were investigated in order to elucidate its potentiality. One eminent aspect of the separation characteristics is the column efficiency. The HETP was increased slowly with the temperature of water mobile phase : a different behavior from that expected from the physical properties such as diffusivity. The other significant aspect of the separation characteristics is the retention behavior of various solutes. The solvent strength of water mobile phase was increased with the temperature and water mobile phase at 190 ℃ corresponded to the mixture of methanol and water (80/20). A new method describing and evaluating the retention selectivity was proposed, in which the retention indices of a set of standard solutes were measured relatively to linear alkane homologs. Taking into account the facts that alkanes are sparingly soluble in hot water and don't respond to … More UV detector, the homologous series of alkyl acetates were used as the reference for measurement of the retention index of any solutes. The retention indices of the former was determined by the calculation using a monoacetate and a diacetate. Five standard solutes of different types were chosen by reference to McReynolds' method in GC and so on. The retention vector reflecting the retention selectivity had the contributions of five different functional groups as element, which were determined as the difference in retention index between a standard solute and the homomorphic hydrocarbon. Some differences in the contribution of the same functional groups were observed between super-heated water and the mixture of methanol-water with comparable solvent strength. The extent of the variation in the retention selectivity with the water temperature was smaller than that with the composition of methanol-water mixture.Simultaneous determination by using plural reactors in series was also discussed for fundamental investigation of advanced techniques of continuous flow analysis using subcritical water. Less