title: Retention modelling in hydrophilic interaction chromatography.
abstract: The retention behaviour of acidic, basic and quaternary ammonium salts and polar neutral analytes has been evaluated on acidic, basic and neutral hydrophilic interaction chromatography (HILIC) stationary phases as a function of HILIC operating parameters such as MeCN content, buffer concentration, pH and temperature. Numerous empirical HILIC retention models (existing and newly developed ones) have been assessed for their ability to describe retention as a function of the HILIC operating parameters investigated. Retention models have been incorporated into a commercially available retention modelling programme (i.e. ACD/LC simulator) and their accuracy of retention prediction assessed. The applicability of HILIC modelling using these equations has been demonstrated in the two-dimensional isocratic (i.e. buffer concentration versus MeCN content modelling) and one-dimensional gradient separations for a range of analytes of differing physico-chemical properties on the three stationary phases. The accuracy of retention and peak width prediction was observed to be comparable to that reported in reversed-phase chromatography (RPC) retention modelling. Intriguingly, our results have confirmed that the use of gradient modelling to predict HILIC isocratic conditions and vice versa is not reliable. A relative ranking of the importance of the retention and selectivity of HILIC operating parameters has been determined using statistical approaches. For retention, the order of importance was observed to be organic content > stationary phase > temperature ≈ mobile phase pH (i.e. pH 3-6 which mainly effects the ionization of the analyte) ≈ buffer concentration. For selectivity, the nature of the stationary phase > mobile phase pH > buffer concentration > temperature > organic content.
authors.affiliation: Hichrom Ltd, 1 The Markham Centre, Station Road, Theale, Reading Berkshire, RG7 4PE, UK. meuerby@hichrom.com.|Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow, G40RE, Scotland. meuerby@hichrom.com.
authors.forename: Melvin R
authors.initials: MR
authors.lastname: Euerby
authors.affiliation: Hichrom Ltd, 1 The Markham Centre, Station Road, Theale, Reading Berkshire, RG7 4PE, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hulse
authors.affiliation: Novo Nordisk A/S, Novo Nordisk Park, 2760, Måløv, Denmark.
authors.forename: Patrik
authors.initials: P
authors.lastname: Petersson
authors.affiliation: Advanced Chemistry Development Inc. (ACD/Labs), 8 King Street East, Suite 107, Toronto, M5C 1B5, Canada.
authors.forename: Andrey
authors.initials: A
authors.lastname: Vazhentsev
authors.affiliation: Advanced Chemistry Development Inc. (ACD/Labs), 8 King Street East, Suite 107, Toronto, M5C 1B5, Canada.
authors.forename: Karim
authors.initials: K
authors.lastname: Kassam
keywords: Design of experiments; Hydrophilic interaction chromatography; Influence of operating parameters; Method development strategy; Retention and peak width modelling; Retention behaviour