Capillary Column Choice and Separation Optimization

There are no hard-and-fast rules for the choice of columns for GC-MS coupling. The choice of the correct phase is made on the typical criterion like dissolves like . If substances exhibit no interaction with the stationary phase, there will be no retention and the substances leave the column at the dead time or get hardly separated from each other. The polarity of the stationary phase should correspond to the polarity of the substances being separated (see Table 2.25). Less polar substances are better separated on non-polar phases and vice versa. 

An exception to this general rule of thumb is given with the newly developed ionic liquid stationary phases. The characteristics and guide to potential applications are discussed in a separate section at the end of this chapter. 

50% diphenyl 50% dimethyl polysiloxane 50% phenyl 50% dimethyl arylene siloxane 65% phenyl 35% dimethyl polysiloxane 

33% cyanopropylphenyl 67% dimethyl polysiloxane 50% cyanopropylphenyl 50% dimethyl polysiloxane 25% cyanopropyl 25% dimethyl polysiloxane 

50% cyanopropyl 50% phenyl- DB-225, HP-225 methyl polysiloxane 70% cyanopropyl polysllphenylene-slloxane 70% blscyanopropyl/ 30% cyano- -propylphenyl polysiloxane 78% cyanopropyl 22% dimethyl polysiloxane 

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