50% methylphenylsilicone phase

Adsorption of 1,4-dichlorobenzene on a model 50% methylphenylsilicone phase. Small white, large white, light-gray, black, and dark-gray balls represent hydrogen, silicone, carbon, o>ygen, and chlorine, respectively. 

A polyethylene oxide with 50% methyl and phenyl groups was prepared and put side by side as a model 50% methylphenylsilicone phase (OV17). The structure is shown in Figure 4.12, where 1,4-dichlorobenzene is adsorbed on the surface. 

PCBZs demonstrated different behavior from other compounds on the 50% methylphenylsilicone phase. The behavior of PCBZs, indicated by AMIVW, was similar to that of PAHs and that of PMBZs, and PMBZs were similar to allqtl alcohols, as shown in Figure 4.16, where experimental data measured at 200 °C is presented. The alkane MIVW was used as the standard, and the difference of the MIVW for other compounds was related to the optimized energy values for a pair of compounds. The combined energy values of molecular interaction (MIVW) and Avap were related to log k values measured at 200 °C, as shown in Figure 4.16. 

Oshima, T., Yoon, H.-S. and Koizumi, C. (1989) Application of selective ion monitoring to the analysis of molecular species of vegetable oil triacylglycerols separated by open-tubular column GLC on a methylphenylsilicone phase at high temperature. Lipids, 24, 535 4. 

Figure 2. Capillary-column gas chromatogram of the total polynuclear hydrocarbon fraction of air-particulate matter ). Conditions 11 m X 0.26 mm -i.d. glass capillary coated with SE-52 methylphenylsilicone stationary phase see Table 1 for...

The stationary phase consists of a thin layer (ca. 0.2 pm) of a non-volatile liquid, such as methylsilicone or methylphenylsilicone, tightly adsorbed to the inert surfaces of the column. The liquid stationary phases are classified according to their polarity, non-polar phases are used most often because they are easier to handle and are stable over a wide temperature range. The mobile phase is an inert carrier gas such as nitrogen, helium or hydrogen which flows at a constant, but adjustable rate through the column. Current capillary columns, with internal diameters between 0.1-0.6 mm, are constructed of fused silica, specially prepared from pure silicon tetrachloride, and formed into spirals up to 100 m long. Injectors, columns and detectors are located in separately thermostatable compartments. 

The chromatographic separation of chlorinated pesticides has been performed with packed columns until the late 1970s to early 1980s, the liquid phases most commonly used being siliconic phases. The operating isothermal temperature was in most cases around 200°C. Nowadays for the GC analysis of chlorinated pesticides fused silica capillary columns are exclusively used. The nonpolar siliconic stationary phases (methylphenylsilicon polymer) are the most frequently used. 

Silicone polymers have a long history as stationary phases in gas-liquid (partition) chromatography (GC). Thus poly(dimethylsiloxane) and methylphenylsilicones provide the useful SE and OV series of phases. More recently, small-molecule LC phases and their blends with OV materials have been evaluated. The occurrence of ordering (e.g. nematic or smectic) in a stationary phase is itself beneficial but, in addition, different separation criteria seem to apply with LC phases. Whereas relative volatility of analyte components dominates separations on ordinary SE or OV columns, molecular shape becomes significant when LC phases are employed (e.g. in the resolution of the isomeric ben-zo[a]pyrene and benzo[e]pyrene). ... 

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