Literature

DryLab draws on the philosophy described in the three most famous Solvophobic Theory papers IIIIII of Csaba Horváth, which were developed in the years 1975-1977 at Yale University (see also literature by Dr. Imre Molnár). Read more about the Fundamentals of DryLab...

Keyword Year

Design of optimized high-performance liquid chromatographic gradients for the separation of either small or large molecules : III. An overall strategy and its application to several examples

B.F.D. Ghrist, L.R. Snyder
J. Chromatogr. A, 459, 43-63 (1988), DOI: 10.1016/S0021-9673(01)82016-1

http://www.sciencedirect.com/science/article/pi...

Recommendations are presented for an efficient approach to the design of optimized gradients for complex samples using computer simulation. Examples based on the separation of polyaromatic hydrocarbon and ribosomal protein mixtures are shown.


Solvent-strength selectivity in reversed-phase HPLC

L. R. Snyder, M. A. Quarry, J. L. Glajch
Chromatographia, 24, 1, 33-44 (1988), DOI: 10.1007/BF02688465

Keywords: Retention optimization, Solvent-strength selectivity

http://link.springer.com/article/10.1007/BF0268...

Solvent-strength selectivity refers to the variation of band spacing by changing the %-organic in the mobile phase (ion-pair or reversed-phase HPLC). A review of the literature has been combined with new experimental data to illustrate the general potential of this approach for HPLC optimization. It appears that most samples exhibit significant changes in band spacing method development based on solvent-strength optimization plus computer simulation (DryLab software) are given for illustration. For relatively simple mixtures (10 or fewer components), it appears that solvent-strength optimization compares favorably with other methods such as mapping the organic-solvent selectivity of methanol, acetonitrile, tetrahydrofuran, and water.


Computer simulation as a means of developing an optimized reversed-phase gradient-elution separation

J. W. Dolan, L. R. Snyder, M. A. Quarry
Chromatographia, 24, 1, 261-276 (1987), DOI: 10.1007/BF02688488

Keywords: Gradient elution, Reversed-phase, Method development, Computer simulation, Retention prediction

http://link.springer.com/article/10.1007/BF0268...

A personal-computer program (DryLab G) is described for the simulation of reversed-phase gradient-elution separations. After two experimental gradient runs are carried out initially, this program allows the user to develop a final separation by varying gradient conditions (gradient time, initial and final %-organic in the mobile phase, gradient shape), column dimensions, flowrate and particle size. This approach takes advantage of “solvent-strength selectivity”, as reported recently [28] for isocratic separations. Method development using this procedure can result in better separations with much less effort. Examples of its validation and application are presented.


Predicting bandwidth in the high-performance liquid chromatographic separation of large biomolecules : II. A general model for the four common high-performance liquid chromatography methods

M.A. Stadalius, B.F.D. Ghrist, L.R. Snyder
J. Chromatogr. A, 387, 21–40 (1987), DOI: 10.1016/S0021-9673(01)94511-X

http://www.sciencedirect.com/science/article/pi...

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


HPLC Method Development and Column Reproducibility, J.W. Dolan, L.R. Snyder, and M.A. Quarry, Am. Lab., 19(8), 43 (1987).

J.W Dolan, L.R Snyder
Am. Lab., 19, 8, 43 (1987)

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.


Band-spacing in reversed-phase high-performance liquid chromatography as a function of solvent strength: A simple and fast alternative to solvent optimization for method development

M.A. Quarry et. al
J. Chromatogr. A, 384, 163–180 (1987), DOI: 10.1016/S0021-9673(01)94668-0

http://www.sciencedirect.com/science/article/pi...

Numerous reports have described the use of solvent optimization for isocratic reversed-phase high-performance liquid chromatography method development. Solvent optimization involves the use of different solvents (usually methanol, acetonitrile and tetrahydrofuran) to control band-spacing for maximum resolution of the sample. Here, we examine an alternative approach, based on variation of the concentration of organic solvent in the mobile phase (solvent strength). This procedure is less powerful than classical solvent optimization, but it nevertheless possesses a significant ability to effect changes in band-spacing. It is also much more easily carried out. Many samples do not require solvent optimization, and in these cases, a change in solvent strength may be the more practical approach.

The retention data required for solvent-strength optimization are most conveniently collected by using two initial gradient runs. The application of gradient retention data for developing a final isocratic separation is facilitated by the use of commercial software. The advantages and limitations of gradient-retention data for this purpose are examined.


Computer Simulation in HPLC Method Development. Reducing the Error of Predicted Retention Times

L. R. Snyder, M. A. Quarry
Journal of Liquid Chromatography, 10, 8-9, 1789-1820 (1987), DOI:10.1080/01483918708066799

http://www.tandfonline.com/doi/pdf/10.1080/0148...

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. 

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