Abstract: A progressive cellular architectures has been presented for vapor-phase chemical analyzers. The progressive cellular architecture consists of a series of heterogeneous micro-gas chromatography cells. Each individual cell targets vapor species within a specific volatility range by using a unique combination of a preconcentrator and a separation column. The cells are connected progressively in series to cover a broad range of volatile analyte chemical vapors. Valves may inadvertently absorb or adsorb and subsequently release target chemical analyte molecules, thereby interfering with quantitative analysis. Therefore, the inlet to the cells is configured without a valve.

Abstract: A progressive cellular architectures has been presented for vapor-phase chemical analyzers. The progressive cellular architecture consists of a series of heterogeneous micro-gas chromatography cells. Each individual cell targets vapor species within a specific volatility range by using a unique combination of a preconcentrator and a separation column. The cells are connected progressively in series to cover a broad range of volatile analyte chemical vapors. Valves may inadvertently absorb or adsorb and subsequently release target chemical analyte molecules, thereby interfering with quantitative analysis. Therefore, the inlet to the cells is configured without a valve.

Abstract: Provided is a method for preparing an epoxide by halohydrination, the method comprising: (1) halohydrination: adding H2O, a halogen(s) and an olefin compound to a reaction device for reaction to obtain a halohydrin; (2) saponification: saponificating the halohydrin with an alkali metal hydroxide to obtain an epoxide and an alkali metal halide; (3) performing a bipolar membrane electrodialysis of the alkali metal halide to obtain an alkali metal hydroxide and a halogen hydride. Also provided is a method for preparing an epoxide by halohydrination, the method comprising: (1) halohydrination: halohydrinating a halogen hydride, an H2O2 and an olefin compound to obtain a halohydrin; optionally, (2) saponification: saponificating the halohydrin with an alkali metal hydroxide to obtain an epoxide and an alkali metal halide; optionally, (3) performing a bipolar membrane electrodialysis of the alkali metal halide to obtain an alkali metal hydroxide and a halogen hydride.