title: Development of an achiral supercritical fluid chromatography method with ultraviolet absorbance and mass spectrometric detection for impurity profiling of drug candidates. Part I: Optimization of mobile phase composition.
abstract: Supercritical fluid chromatography (SFC) is a very useful tool in the purpose of impurity profiling of drug candidates, as an adequate selection of stationary phases can provide orthogonal separations so as to maximize the chances to see all impurities. The purpose of the present work is to develop a method for chemical purity assessment. The first part, presented here, focuses on mobile phase selection to ensure adequate elution and detection of drug-like molecules, while the second part focuses on stationary phase selection for optimal separation and orthogonality. The use of additives in the carbon dioxide - solvent mobile phase in SFC is now commonplace, and enables in particular to increase the number of eluted compounds and to improve peak shapes. The objective of this first part was to test different additives (acids, bases, salts and water) for their chromatographic performance assessed in gradient elution with a diode-array detector, but also for the mass responses obtained with a single-quadrupole mass detector, equipped with an electrospray ionization source (Waters ACQUITY QDa). In this project, we used a selection of one hundred and sixty compounds issued from Servier Research Laboratories to screen a set of columns and additives in SFC with a Waters ACQUITY UPC(2) system. The selected columns were all high-performance columns (1.7-1.8μm with totally porous particles or 2.6-2.7μm with superficially porous particles) with a variety of stationary phase chemistries. Initially, eight additives dissolved in the methanol co-solvent were tested on a UPC(2) ACQUITY UPC(2) HSS C18 SB column. A Derringer desirability function was used to classify the additives according to selected criteria: elution capability, peak shapes, UV baseline drift, and UV and mass responses (signal-to-noise ratios). Following these tests, the two best additives (ammonium acetate and ammonium hydroxide) were tested on a larger number of columns (10) where the two additives appeared to provide very comparable overall scores. However, ammonium acetate was selected for slightly better chromatographic quality. In a second step, we investigated the effects of ammonium acetate concentration (between 0 and 25mM in the methanol co-solvent) on retention and peak efficiency. Two types of silica supports were tested by working with ACQUITY UPC(2) HSS C18 SB and BEH columns. 20mM ammonium acetate in methanol with 2% water was finally selected as the best co-solvent composition.
authors.affiliation: Université d'Orléans, Institut de Chimie Organique et Analytique (ICOA), CNRS UMR 7311, Pôle de Chimie, rue de Chartres, B.P. 6759, 45067 Orléans Cedex 2, France.
authors.forename: Elise
authors.initials: E
authors.lastname: Lemasson
authors.affiliation: Institut de Recherches Servier, 11 rue des Moulineaux, 92150 Suresnes, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Bertin
authors.affiliation: Institut de Recherches Servier, 11 rue des Moulineaux, 92150 Suresnes, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Hennig
authors.affiliation: Waters Corporation, 5 rue Jacques Monod, 78280 Guyancourt, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Boiteux
authors.affiliation: Université d'Orléans, Institut de Chimie Organique et Analytique (ICOA), CNRS UMR 7311, Pôle de Chimie, rue de Chartres, B.P. 6759, 45067 Orléans Cedex 2, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Lesellier
authors.affiliation: Université d'Orléans, Institut de Chimie Organique et Analytique (ICOA), CNRS UMR 7311, Pôle de Chimie, rue de Chartres, B.P. 6759, 45067 Orléans Cedex 2, France. Electronic address: caroline.west@univ-orleans.fr.
authors.forename: Caroline
authors.initials: C
authors.lastname: West
mesh_terms: D000085:Acetates; D002245:Carbon Dioxide; D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D004340:Drug Contamination; D013058:Mass Spectrometry; D000432:Methanol; D004364:Pharmaceutical Preparations / Q000737:chemistry; D016062:Porosity; D059629:Signal-To-Noise Ratio; D012822:Silicon Dioxide; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
chemical_list: D000085:Acetates; D004364:Pharmaceutical Preparations; D012997:Solvents; D002245:Carbon Dioxide; D012822:Silicon Dioxide; C018824:ammonium acetate; D000432:Methanol
keywords: Additives; Derringer desirability functions; Mass detection; Mobile phase composition; Pharmaceutical ingredients; Supercritical fluid chromatography