title: Comprehensive analysis of pharmaceutical products using simultaneous mixed-mode (ion-exchange/reversed-phase) and hydrophilic interaction liquid chromatography.
abstract: Liquid chromatographic assays were developed using a mixed-mode column coupled in sequence with a hydrophilic interaction liquid chromatography column to allow the simultaneous comprehensive analysis of inorganic/organic anions and cations, active pharmaceutical ingredients, and excipients (carbohydrates). The approach utilized dual sample injection and valve-mediated column switching and was based upon a single high-performance liquid chromatography gradient pump. The separation consisted of three distinct sequential separation mechanisms, namely, (i) ion-exchange, (ii) mixed-mode interactions under an applied dual gradient (reversed-phase/ion-exchange), and (iii) hydrophilic interaction chromatography. Upon first injection, the Scherzo SS C18 column (Imtakt) provided resolution of inorganic anions and cations under isocratic conditions, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counterions and potential degradants. At the top of the mixed-mode gradient (high acetonitrile content), the mobile phase flow was switched to a preconditioned hydrophilic interaction liquid chromatography column, and the standard/sample was reinjected for the separation of hydrophilic carbohydrates, some of which are commonly known excipients in drug formulations. The approach afforded reproducible separation and resolution of up to 23 chemically diverse solutes in a single run. The method was applied to investigate the composition of commercial cough syrups (Robitussin®), allowing resolution and determination of inorganic ions, active pharmaceutical ingredients, excipients, and numerous well-resolved unknown peaks.
authors.affiliation: Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Artaches A
authors.initials: AA
authors.lastname: Kazarian
authors.forename: Pavel N
authors.initials: PN
authors.lastname: Nesterenko
authors.forename: Phimpha
authors.initials: P
authors.lastname: Soisungnoen
authors.forename: Rodjana
authors.initials: R
authors.lastname: Burakham
authors.forename: Supalax
authors.initials: S
authors.lastname: Srijaranai
authors.forename: Brett
authors.initials: B
authors.lastname: Paull
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000838:Anions / Q000032:analysis; D002241:Carbohydrates / Q000737:chemistry; D002412:Cations / Q000032:analysis; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D002853:Chromatography, Liquid; D056148:Chromatography, Reverse-Phase; D005100:Expectorants / Q000032:analysis; D006140:Guaifenesin / Q000032:analysis; D057927:Hydrophobic and Hydrophilic Interactions
chemical_list: D000097:Acetonitriles; D000838:Anions; D002241:Carbohydrates; D002412:Cations; D005100:Expectorants; D006140:Guaifenesin; C032159:acetonitrile
keywords: Comprehensive analysis; Hydrophilic interaction liquid chromatography; Mixed-mode columns; Pharmaceutical preparations