Simulation of elution profiles in liquid chromatography - III. Stationary phase gradients

A previously developed liquid chromatographic simulator (see parts I and II) [1-3] is extended to allow for simulations of stationary phase gradients with isocratic and gradient mobile phases. Gradient stationary phases have recently been proposed as means of engineering unique chromatographic selectivities. In the present work, the simulator provides retention times and peak widths that agree with closed form theory for a linear gradient in retention factor and provides accurate retention time predictions for experimentally implemented continuous and discontinuous gradients. Calculation of discontinuous gradients implemented using the commercially available POPLC system have shown good agreement with experiment, with the largest deviation of the simulated retention time from experiment of 4.5%. In addition, simulations of a novel continuous amine gradient column show good agreement with experiment, and give insights into synergistic interactions on column. With the exception of solutes that show evidence of synergistic interactions, the simulated retention times are in agreement with the 95% confidence limits of the experimental values.