Isothermal separation, high-speed

Figure 13.4 Two-dimensional GC separation of isoprene, interference hydrocarbons, and DMS, with the inset showing the one-dimensional separation of isoprene and interference hydrocarbons for comparison. Reprinted from Environmental Science and Technology, 31, A. C. Lewis et ai, High-speed isothermal analysis of atmospheric isoprene and DMS using online two-dimensional gas cliromatography , pp. 3209-3217, copyright 1997, with permission from the American Chemical Society.

FIGURE 5.21 High-speed isothermal separation of a 20-component mixture using a pressure-tunable column ensemble. The plots of band position versus time were obtained from the retention factors for the mixture components on the two separate colimms along with the column dimensions and the inlet, outlet and junction point pressures. A window diagram was used to determine the junction point pressure for the complete separation of the first 14 components. Compounds are 1, n-pentane 2, methyl alcohol 3, 2,2-dimethylbntane 4, 1,1,1-trichloroethane 5, cyclopentane 6, w-hexane 7, w-propyl alcohol 8, cyclohexane 9, benzene 10, n-heptane 11, l,2-dichloropropane 12, toluene 13, n-bntyl alcohol 14, w-octane 15, 2-hexyl alcohol 16, n-pentyl alcohol 17, ethylbenzene 18, m-xylene 19, w-nonane 20, o-xylene. 

FIGURE 5.22 High-speed isothermal separation of the 20-component mixmre from Figure 21 except that the junction-point pressnre was decreased 21 s after injection to obtain the complete separation of the mixture. 

FIGURE 5.25 High-speed isothermal separation of a 13-component mixture without stop-flow operation (a), with a 2-s-wide stop-flow pulse to separate components (1 and 2), (b) and (c) with three stop-flow pulses to separate component pairs (1,2), (10,11), and (12,13). Vacuum outlet GC was used with an outlet pressure of 0.5 atm., and atmospheric-pressure air was used as carrier gas. Components are 1, ethyl acetate 2,2-butanone 3, benzene 4, 1-butanol 5, trichloroethylene 6, n-heptane 7, 2,5-dimethylfuran 8, 2,4-dimethylhexane 9, 3-methyl-l-butanol 10, toluene 11, 2-methylheptane 12, butyl-acetate 13, chlorobenzene. 

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