Program for the interpretive optimization of two-dimensional resolution.

The challenge of fully optimizing LC×LC separations is horrendous. Yet, it is essential to address this challenge if sophisticated LC×LC instruments are to be utilized to their full potential in an efficient manner. Currently, lengthy method development is a major obstacle to the proliferation of the technique, especially in industry.

Correction of the deviations in the retention times with Chromolith columns associated to the flow rate: implications in the modelling of the retention behaviour.

In a previous work (J. Sep. Sci.

Determination of the hydrophobicity of organic compounds measured as logP(o/w) through a new chromatographic method.

A new chromatographic method to determine the octanol-water partition coefficient (logP(o/w)) of organic substances is proposed in this paper. This method is based on a previously reported model that relates the retention factor in reversed-phase liquid chromatography with solute (p), mobile phase (P(m)(N)) and stationary phase (P(s)(N)) polarity parameters: logk=(logk)(0)+p(P(m)(N)-P(s)(N)). P(m)(N) values are calculated through expressions that depend only on the organic solvent fraction in the mobile phase.

Performance of a Chromolith RP-18e column for the screening of beta-blockers.

The chromatographic performance of a monolithic column (Chromolith RP-18e) was comprehensively examined in the isocratic separation of ten beta-blockers, using ACN-water mobile phases, and compared with the performance of three microparticulate RP columns manufactured with different types of silica: Spherisorb ODS-2, Kromasil C18 and XTerra MS C18. The comparison considered the analysis time, selectivity, peak shape (column efficiency and asymmetry) and resolution, and was extended to a wide range of mobile phase compositions. The Chromolith column showed good performance for the analysis of beta-blockers with regard to the packed columns.

Interpretive optimisation of organic solvent content and flow-rate in the separation of beta-blockers with a Chromolith RP-18e column.

The chromatographic performance of a Chromolith RP-18e column was comprehensively examined for a group of basic drugs (beta-blockers), eluted with isocratic ACN-water mixtures at increasing flow-rate up to 6 mL/min. As the flow-rate increases at fixed mobile phase composition, peak distribution (selectivity) is maintained, but the relative peak widths increase. This reduces the resolution below satisfactory values for closely eluting compounds.