2020 Volume 69 Issue 3 Pages 135-139
In two-dimensional LC (2D-LC), a combination of different separation modes is effective for increasing the peak capacity. However, for example, in the combination of reversed-phase chromatography (RPC) and hydrophilic interaction chromatography (HILIC), the elution strength of the organic solvent in the mobile phase is contradictory, so that the compatibility of the mobile phase, such as deterioration of the peak shape in the second dimension, is often a problem. On-line diluting of an eluate from the first dimension is a well-known procedure, but it has drawbacks, such as a complicated system. Recently, a new valve, which has the function of splitting the second-dimensional mobile phase was developed. By using this valve, we investigated the effect on improving the second-dimensional peak shape. As a result, it was confirmed that the flow split/on-line dilution method is effective for improving the peak shape of the second dimension in 2D-LC, such as RPC → HILIC and gel permeation chromatography (GPC) → gradient polymer elution chromatography (GPEC).