Page 390 - Multidimensional Chromatography
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382                                     Multidimensional Chromatography



























                           Figure 14.2 Schematic diagram of the chromatographic system used for the analysis of low
                           concentrations of sulfur compounds in ethene and propene: V1, injection valve; V2, column
                           switching valve; SL, sample loop; R, restriction to replace the column; SCD, sulfur chemilu-
                           minescence detector.


                             A more sensitive separation scheme is presented in Figure 14.4. This valveless
                           switching system was originally developed by Deans (10, 11) and utilizes pressures
                           to direct the flows through the different columns. Two capillary columns are used, of
                           which the first separates the hydrocarbons from each other and from the sulfur gases.



                                                                       2
                                                          1

                                    Detector response












                                     0             1              2            3
                                                       Retention time (min)
                           Figure 14.3 Chromatographic separation of sulfur compounds in propene, obtained by
                           using the system illustrated in Figure 14.2: 1, hydrogen sulfide; 2, carbonyl sulfide.
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