Normal-phase liquid chromatography cyano column

Antidepressant separation was usually performed by reversed-phase chromatography with typical C8 or C18 alkyl chain columns, although phenyl [30, 59] or cyano [48,64, 84] stationary phases were also employed. As an exception, hydrophilic interaction liquid chromatography (HILIC), a variation of normal phase chromatography, was employed in two analytical methods for duloxetine [38] and... 

E. L. Weiser, A. W. Salotto, S. M. Flach, and R. L. Snyder, Basis of retention in normal-phase high-performance liquid chromatography with cyano-propyl columns, J. Chromatogr. 303 (1984), 1-12. 

Reversed-phase high-performance liquid chromatography (RP-HPLC) is more popular for analysis of carotenoids than is normal-phase HPLC because (1) retention is very little affected by small variations in the mobile-phase composition, and (2) the risk of artifact formation on passage through the column is minimal as solute-support interactions on non-polar-bonded phases only involve weak forces. A variety of stationary phases of various polarities are available, such as C18, C8, C4, C2, Cl, phenyl, and cyano derivatives the C18 phase is the most popular. 

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