A general model for describing gradient elution separations of peptides and proteins by reversed-phase high-performance liquid chromatography (HPLC) has been presented previously. This model has now been modified so that it can be applied to any of the four HPLC methods used for separating biological macromolecules: reversed-phase, ion-exchange, hydrophobic-interaction and size-exclusion chromatography, carried out in either an isocratic or gradient elution mode. The role of sample molecule structure and the particular column used has been further studied, so that previous empirical parameters for different column/sample choices can now be estimated from three physical properties of the sample and the column: (a) sample molecular weight, (b) native vs. denatured sample, (c) column packing pore diameter. This eliminates much of the empiricism of our preceding model, and minimizes the number of experimental runs now required in order to apply the model in practice

Application of DryLab 4-5 (the first DryLab program to model retention effects) to the problem of column-to-column reproducibility, adjusting conditions to minimize retention differences.

Computer simulation uses two experimental HPLC runs to allow prediction of sample retention as a function of mobile phase composition or gradient conditions. The general approach is rigorous, but it is assumed that reversed-phase retention obeys the relationship log k' = log kw - S 0. Small deviations in this relationship can lead to error in predicted retention times. We have studied this error empirically for several different reversed-phase systems. This provides a basis for partially correcting these errors, and suggests recommendations for avoiding significant errors during computer simulation.Further work on improving the accuracy of DryLab I and DryLab G predictions, verification of this approach. 

Column plate numbers, N, were measured for 12 different proteins as a function of mobile phase flow-rate in two gel filtration systems (either denaturing or non-denaturing conditions). These data were used to extend a previous model that predicts bandwidths in reversed-phase and ion-exchange chromatography. Restriction of diffusion of large molecules within column packing pores is now defined more precisely, with a single relationship describing this effect for both reversed-phase and size-exclusion chromatography (SEC) (and presumably other high-performance liquid chromatography systems). Separations by gel filtration (SEC) are now included in our general model. A total of 17 flow-rate studies were carried out, involving different proteins, columns and/or mobile phase conditions (denaturing or non-denaturing). Comparisons of plate numbers predicted by the model with experimental values were satisfactory in 15 out of 17 cases. The remaining two cases appear to represent "non-well-behaved" systems, where experimental bandwidths were higher than predicted values by more than 20%. Initial attempts at understanding the origin of these non-ideal effects are described.

First description of DryLab 1 (the ancestor of the column optimization portion of the present DryLab for Windows) as applied to a steroid sample.