Live switching

Table 10.1 Applications of MDGC reported by Mosandl and his co-workers. These were developed by using a Siemens SiChromat 2 double-oven system with two independent temperature controls, two flame-ionization detectors and a live switching coupling piece, employing the heartcutting technique...

Figure 8.18 Schenatic diagram of a dual oven two-dimensional gas chromatograph employing live switching between two capillary columns. (Reproduced with permission from Siemens AG).

A more st histicated instrument employing two independent temperature controlled ovens with sample transfer by live switching is shown in Figure 8.18 (198,213,214,219-222). The... 

Figure 8.19 Two-diaenslonal separation of the components of a coal derived gasoline fraction using live switching. Column A was 121 n open tubular column coated with poly(ethelene glycol) and column B a 64 m poly(dimethylsiloxane) thick film column. Both columns were temperature programmed independently taking advantage of the two oven configuration. Peak identification 1 acetone, 2 2-butanone, 3 > benzene, 4 isopropylmethylketone, 5 isoprop-anol, 6 ethanol, 7 toluene, 8 => propionitrile, 9 acetonitrile, 10 isobutanol, 11 — 1-propanol, and 12 = 1-butanol. (Reproduced with permission from Siemens AG).

The design has been well proved in quality assurance and origin control of flavours and fragrances. A double-oven system is shown in the Fig. 17.3, with two independent temperature controls and two detectors (DM 1, DM 2). A live switching coupling piece is used to switch the effluent flow to either the first detector or the chiral column. With optimum pneumatic adjustment of the MDGC system, certain fractions are selectively transferred onto the chiral main column as they are eluted from the precolumn (heart-cutting technique) [15]. 

Figure 4 Flame ionization detector chromatogram a capillary column system with Live-switching equipment. (A) Separation by porous polymer column 1, carbon dioxide 2, ethene 3, ethyne 4, ethane. (B) Separation by molecular sieve column 5, carbon monoxide. (C) Separation by WCOT column 6, methane 7, ethane (ethene, ethyne) 8, propene 9, propane 10, /-butane 11, /> butane 12, neopentane 13, /-pentane 14, n-pentane 15, 2,2-dimethylbutane and cyclopentane 16, 2,3-dimethylbutane 17,3-methylpentane 18, n-hexane 19, benzene 20, cyclohexane 21, n-heptane 22, toluene 23, />octane 24, xylene.

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