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2.7.2.4.1. Stationery phase
Stationery phase materials are spherical particles of uniform size. They are made of chemically modified silica, alumina or styrene/divinylbenzene copolymers. They exist in three forms:
1. Normal-phase partition chromatography Normal phase has a highly polar stationary phase made of triethylene glycol or water. Mobile phase should be non-polar solvent such as hexane or i-propyl ether. As the compound polarity decreases or solvent polarity increases, the retention time will decrease. 2. Reversed-phase partition chromatography Reverse phase is very common and has a non-polar stationary phase made of hydrocarbon. Mobile phase should be polar solvent such as water, ethanol, acetonitrile or tetrahydrofuran. As the compound polarity decreases or solvent polarity increases, the retention time will increase. |