A RP-HPLC method for simultaneous determination of calcium pantothenate and two preservatives methylparaben and propylparaben present in topical cream was developed. Different analytical columns with various stationary phases were tested. During method development, Supelco Discovery C18 column (125 mm × 4.0 mm, 5 μm) and Zorbax SB-CN column (150 mm × 4.6 mm, 5 μm) were tested. Both were not convenient for analytical separation because of the co-elution of calcium pantothenate with dead volume, and problems with the peak-shape of all components. Good separation was achieved using Zorbax TSM (250 mm × 4.6 mm, 5 μm) and Hypersil ODS column (250 mm × 4.6 mm, 5 μm), the latter was finally used for the analysis. The analysis time was 12 min, at flow rate 0.7 ml min−1. Chromatography was performed using binary mobile phase composed of methanol and phosphoric acid, pH 2.5, 65:35 (v/v). UV detection was accomplished at 214 nm. The method was validated according to ICH guideline recommendations.
The method is suitable for practical routine analysis of commercially produced topical pharmaceutical preparations.