Área de trabajo: Farmacéutica.
Título: Determinación simultánea de Metformina y de su Contraión de Cloruro usando Cromatografía Líquida multimodo con Detección por Aerosol Cargado.
Título original: Simultaneous Determination of Metformin and its Chloride Counterion Using Multi-Mode Liquid Chromatography with Charged Aerosol Detection.
Autor: Xiaodong Liu and Mark Tracy, Thermo Fisher Scientific, Sunnyvale, CA, USA.
Determinations of Active Pharmaceutical Ingredients (API) and counterions are important assays in pharmaceutical analysis. Due to the difference in charge and/or hydrophobicity, APIs and couterions are usually analyzed by different chromatographic methods that require different separation columns and/or different instrumentation platforms. Metformin is an oral antidiabetic drug, often formulated in its hydrogen chloride salt form. Because of the highly hydrophilic nature of both API and counterion, it is impossible to assay both components within the same analysis on any RP, ion exchange or HILIC column.
The Acclaim Trinity P2 column is based on Nanopolymer Silica Hybrid (NSH™) technology. It consists of high-purity porous spherical silica particles coated with charged nanopolymer particles: the inner-pore area of the silica particles is modified with a covalently bonded hydrophilic layer that provides cation exchange retention while the outer surface is modified with anion-exchange nano-polymer beads. This chemistry design ensures spatial separation of the anion exchange and cation exchange regions.
Since Acclaim Trinity P2 columns provide both cation-exchange and anion-exchange retention mechanisms at the same time, they can adequately retain both metformin (cationic) and chloride (anionic) under the same chromatographic conditions. The unique chemistry of the Acclaim Trinity P2 column, in which cation-exchange and anion-exchange regions are spatially separated, allows for great flexibility in method optimization by adjusting mobile phase buffer concentration, pH, and/or organic solvent content. To optimize this particular application, various buffer concentrations and solvent levels were examined by proportioning acetonitrile, 100 mM ammonium formate buffer and de-ionized water. Several separation conditions were developed. The best result, according to the criteria of retention (k > 2), resolution (Rs > 2) and analysis time (<10 min), was achieved at 80% acetonitrile and 20% buffer, demonstrated in Figure 1.
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