For complex samples, monodimensional HPLC often do not provide enough separation and its identification power is limited.Multidimensional (MD) HPLC can help in overcoming these limitations.On-line multidimensional HPLC systems usually consist of two columns (ideally with orthogonal separation mechanisms) coupled via a switching valve used as interface, that permits the transfer of specific volumes of 1D effluent onto the secondary column.When used in comprehensive mode, with the multidimensional advantages extended to the whole sample, the MD HPLC analysis offers enhanced peak capacity and identification power due to the formation of group type patterns on the 2D plane.