Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5135744 | Journal of Chromatography A | 2016 | 11 Pages |
Abstract
The mixing rate (RÏ) is the temporal rate of increase in the solvent strength in gradient LC. The optimal RÏ (RÏ,Opt) is the one at which a required peak capacity of gradient LC analysis is obtained in the shortest time. The balanced mixing program is a one where, for better separation of early eluting solutes, the mixing ramp is preceded by a balanced isocratic hold of the duration depending on RÏ. The improvement in the separation of the earlier eluites due to the balanced programming has been evaluated. The value of RÏ,Opt depends on the solvent composition range covered by the mixing ramp and on the column pressure conditions. The RÏ,Opt for a column operating at maximum instrumental pressure is different from RÏ,Opt for a column operating below the instrumental pressure limit. On the other hand, it has been shown that the difference in the RÏ,Opt values under different conditions is not very large so that a single default RÏ previously recommended for gradient analyses without the isocratic hold also yields a good approximation to the shortest analysis time for all conditions in the balanced analyses. With or without the initial balance isocratic hold, the recommended default RÏ is about 5%/t0 (5% increase in the solvent strength per each t0-long increment in time) for small-molecule samples, and about an order of magnitude slower (0.5%/t0) for protein samples. A discussion illustrating the use of the optimization criteria employed here for the techniques other than LSS gradient LC is included.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Leonid M. Blumberg, Gert Desmet,