Two-dimensional HPLC analysis of oligostyrenes: comprehensive and online heart-cutting techniques

2-D HPLC incorporating two reversed phase (RP) environments was employed for the isolation of oligomers and their diastereomers of low molecular weight oligostyrenes. The operation of a comprehensive method of analysis was compared to a heart-cutting approach. The comprehensive approach employed a high resolution diastereomer separation in the first dimension and a low peak capacity C18, high speed separation according to molecular weight. Because of solvent incompatibility between the dimensions in the comprehensive method, successful separation of the diastereomers of the oligomers was not possible. The heart-cutting approach used a C18 monolith in the first dimension, which was selective only for molecular weight. Entire molecular weight fractions were then transported to the second dimension in an online heart-cutting process for the separation of diastereomers. The heart-cutting process was more successful in that 228 components of the 511 within the sample were recognized. This series of separations was undertaken in less than 6 h.