Comparison of equations describing band broadening in high-performance liquid chromatography

Several models are well established that describe band broadening in gas and liquid chromatography, including those due to Van Deemter and Knox. Comparison of competing models is complicated if raw data are noisy or if the equations to be fitted to data contain many adjustable parameters. This paper describes a comparison of fitting the Van Deemter, Knox and other equations to low noise data gathered during the separation of propyl- and methylparaben by HPLC. Equations are compared using established statistical methods, including analysis of residuals, inference of parameter estimates and Akaikes Information Criterion for model identification. This work indicates that equations that account for non-linear band broadening at elevated mobile phase velocities are more successful at describing the relationship between height equivalent to a theoretical plate, H, and the velocity of the mobile phase, u.