Retention prediction in ternary solvent reversed-phase liquid chromatography systems based on the variation of retention with binary mobile phase composition (original) (raw)
Related papers
Analytica Chimica Acta, 1994
Retention data (log k') for 14 benzene and 18 phenol derivatives have been obtained in a C18 column for the full range of methanol-water and acetonitrile-water mobile phase compositions. From the equations developed in an earlier work a new solvent parameter has been calculated from the retention data in the two mobile phases studied. General linear equations have been established which describe chromatographic retention in the full range of mobile phase compositions by a single solute parameter and the new solvent parameter. The applicability of the new solvent parameter to different solutes and C18 columns has been tested with literature data.
Systematic study of ternary solvent behaviour in reversed-phase liquid chromatography
Journal of Chromatography A, 1981
An extensive experimental survey of the retention behaviour of 32 solutes in the system methanol-tetrahydrofuran-water and 49 solutes in the system methanolacetonitrile-water is presented_ The retention data are fitted to a second order sixparameter equation, describing the capacity factor as a function of mobile phase composition. Iso-eluotropic lines, ie., lines that connect solvents of equal eluotropic strength, are constructed in the ternary diagrams for the two systems and compared with theoretical lines, predicted from solubility parameter theory. Specific effects are defined as variations in retention for a particular solute, using solvents of equal eluotropic strength. Such effects appear to be larger between different binary mixtures ihan within the ternary triangle. Ternary solvents thus provide a smooth transition between two limiting binary mixtures.
Analytical Chemistry, 1989
been developed to account for the partltkning of solutes from aqueous moblle phases Into reversed-phase llquld chromatography statlonary phases. Several predictlons are tested here agalnst an extensive data base of nearly 350 sets of experlments. I n agreement with theory, we flnd that (I) the dependence of retention on moblle phase composition can often be sultably Ilnearlzed through use of a type of composltlon plot recently suggested by DIH, (11) retentlon measurements can be used to determlne the blnary lnteractlon constants of solutes with solvents, and (111) El-30 solvent probe experbnents appear to provlde a direct measure of the btnary lnteractlon constants. This work suggests that the slmple ramkmmhtlng approximalkn for solutes wlth solvents Is often useful even for complex chromatographic solutlons.
Journal of Chromatography A, 2002
Six equations that express the combined effect of mobile phase pH and organic modifier content on sample retention in reversed-phase liquid chromatography (RPLC) are developed based on either the adsorption or the partition model for retention. The equations are tested against five retention data sets taken from literature. In the tests two pH scales are used, w s pH and pH. It is shown that a new seven-parameter equation works more satisfactorily, because it exhibits good numerical w s behavior, gives low values of the sum of squares of residuals and represents the experimental retention surfaces successfully. In addition, the danger of overfitting, which leads to the prediction of physically meaningless retention surfaces, is minimized by using the proposed new seven-parameter equation. Finally, the possibility of obtaining reliable pK values of weak acids or bases chromatographically by means of the derived equations is also considered and discussed.
Journal of Chromatography A, 2009
The polarity parameter model previously developed: log k = (log k) 0 + p(P N m − P N s ) has been successfully applied to study several chromatographic systems involving new generation RPLC columns (Luna C18, Resolve C18, XTerra MSC18, and XTerra RP18). In this model the retention of the solutes (log k) is related to a solute parameter (p), a mobile phase parameter (P N m ) and two chromatographic system parameters [P N s and (log k) 0 ]. The studied systems have been characterized with different acetonitrile-water and methanol-water mobile phases, using a set of 12 neutral solutes of different chemical nature. The polarity parameter model allows prediction of retention of any solute in any mobile phase composition just using the retention data obtained in one percentage of organic modifier and the polarity parameters established in the characterization of the chromatographic systems. This model also allows the solute polarity data transference between RPLC characterized systems, so it is possible to predict the retention in various RPLC systems working experimentally with just one of them. Moreover, the global solvation parameter model has also been applied to the same chromatographic systems using a wide set of solutes in order to compare its predictive ability with the one of the polarity parameter model. The results clearly show that both models predict retention with very similar accuracy but the polarity parameter model requires much less preliminary experimental measurements to achieve equivalent results than the global solvation approach.
Journal of Separation Science, 2012
Recent developments in HPLC methods have focused on various strategies in order to increase the speed of analysis. One area of impressive growing is column technology. Today, analytical methods that propose the use of short columns packed with sub-2 mm particles installed in ultra high-pressure LC instruments are not uncommon. Another strategy consisted of heating thermally resistant columns to temperatures well above of 1001C in order to reduce eluent viscosities and, therefore, column backpressure. We discuss experimental conditions for achieving high-throughput analysis using standard instruments with a few simple modifications. The chromatographic performance of two particulated and a silica-based monolithic column operated at moderate temperatures and flow rates are compared. The monolithic column proved to be stable over several thousands column volumes at 601C. More important, its resistance to mass transfer at this temperature was significantly reduced. Very fast separations of two different mixtures of pharmaceutical compounds, anti-inflammatory drugs and b-blockers, were achieved with the three columns at 601C by using ACN/buffer at 5 mL/min. Excellent peak shapes of basic solutes and quite reasonable resolutions were achieved in very short analysis times with columns operated at temperatures moderately higher than the usual room temperature.
Journal of Chromatography A, 2002
A semi-thermodynamic treatment is adopted to account for adsorption or partition of solute molecules from aqueous mobile phases on / in reversed-phase liquid chromatography stationary phases. The theoretical expressions of ln k9 versus organic modifier content are tested against 10 data sets covering a variety of solute molecules. It is shown that the mean field approximation, adopted widely in previous studies, is marginally valid in aqueous mobile phases, especially in the presence of solute molecules, and the lattice model approximation, which is also used in relevant studies, is a poor approximation. Clear conclusions about the validity of either the adsorption or the partition model for the retention mechanism could not be drawn. The equations of the adsorption model describe all data sets absolutely satisfactorily and yield a physically reasonable picture about the behavior of modifier and solvent at the adsorbed layer. However, the high applicability of the adsorption model may not safely entail the validity of the adsorption mechanism at a molecular level, especially in the case of solutes with small and non-polar molecules, where our analysis gives strong indications about the validity of the partition mechanism. The next steps needed for the final elucidation of the retention mechanism in reversed-phase chromatographic columns are indicated.
The Mechanism of Solute Retention In Reversed-Phase Liquid Chromatography
Theory is developed to describe the retention of small molecules by the grafted chain phases used in reversed-phase liquid chromatography. The affinity of the solute for the grafted phase is determined by the entropy of mixing of the solute, the configurational entropy of the grafted chains, and the contact interactions among solute, solvent, and chains, treated here in the random mixing approximation for single or binary eluents. Retention can be predicted from simple physical quantities, such as the oil-water partition coefficient, but generally not from the solvent surface tension alone, as proposed in the "solvophobic theory". These grafted chains are semiordered at the interface; therefore, (i) solutes should partition less into the grafted phase than into amorphous oillike phases, and (ii) hydrophobic solutes should concentrate nearer the free than the grafted ends. It is shown that retention is principally due to solute partitioning into, rather than adsorption onto, the grafted chains.
Acta Chimica Slovenica, 2019
There are several different approaches for LC method development; beside traditional, different software programs for method development and optimization are available. The solvatic retention model of reversed-phase LC was applied for prediction of retention in the gradient elution mode for aripiprazole and its related substances described in European Pharmacopoeia. As some of these compounds have very similar and others quite different chemical structure, their separation is challenge. Prediction was suitable on examined stationary phases (C18, C8 and phenyl-hexyl) with 0.1% phosphoric acid as aqueous mobile phase and acetonitrile or methanol as organic modifier. Predicted retention times take into account structural formulae of compounds and properties of stationary and mobile phases result in average difference of 14-17% compared to experimental ones on phenyl-hexyl stationary phase, where the highest matching was obtained. After utilisation of the retention models with data from one experimental run, the average difference decrease to maximal 7% and after contribution of data from two experimental runs, to maximal 2%. For majority of studied compounds difference between predicted and experimental values on all examined stationary phases is lower than 3%.