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.

Profiling cocaine residues and pyrolytic products in wastewater by mixed‐mode liquid chromatography–tandem mass spectrometry

“…These columns contain long alkyl chain ligands with an ionizable terminus which, depending on the functional groups and the pH of the mobile phase, allow them to interact with the analytes by anion‐exchange, cation‐exchange or both, in addition to RP interactions. Several applications of this technology can be found in the pharmaceutical field and, to a minor extent, in the food and environmental field …”

“…Several applications of this technology can be found in the pharmaceutical field [28][29][30] and, to a minor extent, in the food 31,32 and environmental field. 33,34 The aim of this study was to develop a new analytical method combining SPE and mixed-mode LC coupled to MS/MS for the determination of COC and its related compounds in wastewater.…”

Recent applications of hydrophilic interaction liquid chromatography in pharmaceutical analysis

“…Reproducibility parameters were also assessed for the real samples revealing RSD values of below 1% for intraday and interday reproducibility based on retention time, while the RSDs of peak areas ranged between 5 and 10% for all the studied compounds. While in another study, the mixed‐bed column used was Scherzo SS C18, which provided resolution of inorganic anions and cations under isocratic conditions upon first injection, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counter‐ions and potential degradants . The approach afforded reproducible separation and resolution of up to 23 chemically diverse solutes in a single run.…”

Development and validation of a stability‐indicating HPLC method for topiramate using a mixed‐mode column and charged aerosol detector

“…An alternative to this chromatographic challenge is the application of mixed‐mode chromatography (MMC) to topiramate analysis. MMC has been used in pharmaceutical applications as an alternative tool to more traditional reversed‐phase, ion exchange, and normal‐phase chromatography for analysis of challenging analytes . The dominant interactions of these types of chromatography are hydrophobic, hydrophilic, and ionic, respectively, which contrasts to MMC that combines two or more modes of interaction .…”