Coupling of Physical and Chromatographic Separation for Analyzing Cream Containing Miconazole, Mometasone Furoate and Gentamicin Sulphate.

High-performance liquid chromatographic method was developed, validated and applied for miconazole, mometasone and gentamicin in Momenta® cream. Physical separation was applied using two extraction procedures due to different solubility of the three components. First, a methanolic extract of the cream contained miconazole and mometasone was chromatographed on ODS-3 Inertsil C18 column (150 × 4.6, 5 μm) using acetonitrile: water (80:20, v/v) as a mobile phase, flow rate 1.5 mL·min-1, scanned at 230 nm, showing tR 2.817 and 6.808 min for mometasone and miconazole, respectively. Second, an aqueous extract of the cream containing gentamicin was derivatized with o-phthalaldehyde in order to enhance the gentamicin UV detection and subjected to ion pairing chromatography on Inertsil ODS-3 C18 column (150 × 4.6, 5 μm), using methanol: 0.025 M heptane sulphonic acid: glacial acetic acid (75:20:5, by volume) as a mobile phase, flow rate 0.8 mL·min-1, scanned at 330 nm where the three active gentamicin isomers were separated at tR 11.7, 15.6 and 18.3 min. Suitability of this method for quantitative estimation of the drugs was proved by validation according to ICH guidelines. The method was selective, precise and accurate so could be used for analysis of cream formulation in QC labs.