Reversed Phase HPLC Columns

The figure below shows the strength of the stereoselectivity and the pi-interaction with respect to the holding strength of the reversed-phase column. The retention strength, stereoselection system, and strength of pi-interaction are based on the retention coefficient of amylbenzene, retention ratio of o-terphenyl and triphenylene, and retention ratio of amylbenzene and triphenylene, respectively. These are plotted below. In addition, the polar group-encapsulating (embed) type column provides a large effect on other interactions; thus, it was plotted in the type in order to distinguish it from the other columns.

Selectivity of reversed-phase columns are compared under the same conditions, packing material size and column size. Chemical structural formulas used for the comparison are shown at right. Separation differences between basic compounds, acidic compounds, alkyl benzenes and polyaromatic compounds shows the differences of column selectivity. The more silanol groups on the packing material lead the later elution time of caffeine compared with that of phenol. The higher hydrophobicity of the column shows the later elution time of n-Amylbenzene compared with that of n-Butylbenzene. The higher steric selectivity of the column shows the later elution time of Triphenylene compared with that of o-Terphenyl. 

For Molecular Weight <5,000

For Molecular Weight >5,000

For Highly Polar Compounds