title: A complementary mobile phase approach based on the peak count concept oriented to the full resolution of complex mixtures.
abstract: Situations of minimal resolution are often found in liquid chromatography, when samples that contain a large number of compounds, or highly similar in terms of structure and/or polarity, are analysed. This makes full resolution with a single separation condition (e.g., mobile phase, gradient or column) unfeasible. In this work, the optimisation of the resolution of such samples in reversed-phase liquid chromatography is approached using two or more isocratic mobile phases with a complementary resolution behaviour (complementary mobile phases, CMPs). Each mobile phase is dedicated to the separation of a group of compounds. The CMPs are selected in such a way that, when the separation is considered globally, all the compounds in the sample are satisfactorily resolved. The search of optimal CMPs can be carried out through a comprehensive examination of the mobile phases in a selected domain. The computation time of this search has been reported to be substantially reduced by application of a genetic algorithm with local search (LOGA). A much simpler approach is here described, which is accessible to non-experts in programming, and offers solutions of the same quality as LOGA, with a similar computation time. The approach makes a sequential search of CMPs based on the peak count concept, which is the number of peaks exceeding a pre-established resolution threshold. The new approach is described using as test sample a mixture of 30 probe compounds, 23 of them with an ionisable character, and the pH and organic solvent contents as experimental factors.
authors.affiliation: Polymer Characterization, S.A., c/ Gustave Eiffel 8, València Parc Tecnològic, 46980 Paterna, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Ortín
authors.forename: J R
authors.initials: JR
authors.lastname: Torres-Lapasió
authors.forename: M C
authors.initials: MC
authors.lastname: García-Álvarez-Coque
mesh_terms: D056148:Chromatography, Reverse-Phase / Q000295:instrumentation / Q000379:methods*; D045424:Complex Mixtures / Q000032:analysis / Q000302:isolation & purification*
chemical_list: D045424:Complex Mixtures