Cyano column Normal-Phase Liquid

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. 

P. L. Smith and W. T. Cooper, Retention and selectivity in amino, cyano and diol normal bonded phase high-performance liquid chromatographic columns, J. Chromatogr. 410 (1987), 249-265. 

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