Selectivity of a Native β‐Cyclodextrin Column in the Separation of Catechins

Abstract

Catechins are most commonly analyzed by liquid chromatography using a C₁₈ column and reversed mobile phases, involving hydrophobic interactions. It is showed that a β‐cyclodextrin (β‐CD) column can separate five catechins (catechin, epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin gallate) as well as gallic acid in the reversed phase mode with methanol‐water mobile phases and in the polar organic mode with acetonitrile‐methanol mobile phases. 0.1% v/v of acetic acid had to be added to all mobile phases to improve peak shapes. The selectivity (order of retention of the catechins) is completely different between classical C₁₈ columns and the β‐CD column. This is due to a classical hydrophobic mechanism on C₁₈ column compared to a H‐bond dominated mechanism with β‐CD column in both RPLC and polar organic mode. It is shown that the catechin solutes could be analyzed ten times faster using the low viscosity polar organic mode and a β‐CD column compared to RPLC with a C₁₈ column.

Keywords:

• Cyclodextrin stationary phase
• Catechins of tea
• Polar organic mobile phases
• Reversed phase liquid chromatography