Utilising retention correlation for the separation of oligostyrenes by coupled-column liquid chromatography

The separation of η =2–5 η-butyloligostyrenes has been illustrated by reversed-phase reversed-phase (RP–RP) coupled-column liquid chromatography. The coupled-column separation has been achieved by use of a C₁₈ column with methanol as the mobile phase followed by a DiamondBond C₁₈ column with acetonitrile (ACN) mobile phase. The DiamondBond C₁₈ is a hybrid carbon clad zirconia (CCZ)–C₁₈ stationary phase. Unlike a C₁₈–carbon clad zirconia two-dimensional liquid chromatographic system, which is orthogonal, the C₁₈ and DiamondBond C₁₈ columns combination exhibit correlations based upon the molecular weight of η-butyloligostyrenes. Using an alternative strategy to two-dimensional liquid chromatography, the molecular weight dependence displayed by both the C₁₈ column and DiamondBond C₁₈ has been used to increase throughput or decrease analysis time in the analysis of the η-butyloligostyrenes. However, this is at the expense of a portion of the two-dimensional peak capacity displayed by the C₁₈–carbon clad zirconia system.