title: [Determination of magnesium stearate in pharmaceutical preparations using derivatization with 2-nitrophenylhydrazine and HPLC].
abstract: In general, spectrophotometric methods (inductively coupled plasma or atomic absorption spectrophotometry) are used for the assay of magnesium stearate (Mg-St). In this study, a new rapid, selective assay method was developed for Mg-St in pharmaceutical formulations. The method was based on isocratic reverse-phase liquid chromatography using a mobile phase of acetonitrile-water (80:20, v/v) after precolumn derivatization with 2-nitrophenyl hydrazine for sensitive UV detection. Margaric acid was used as an internal standard and the substances were detectable at 230 nm or 400 nm. Using a short (2 cm) HPLC column reduced the analytical time to 5 min. Validation of the newly developed method was performed in accordance with the International Conference on Harmonization guidelines. The linearity range for Mg-St was 0.00-0.04 mg/ml (as the concentration of injected sample solution) and their correlation factor was 0.9998. The determination and detection limits for Mg-St were 6 microg and 2 microg, respectively. The proposed method was successfully applied to the determination of trace amounts of Mg-St in commercially available tablets with a high recovery percentage, good accuracy, and precision.
authors.affiliation: Pharmaceutical Technology Research Laboratories, Tokyo Pharmaceutical Research Center, Daiichi Pharmaceutical Co., Ltd., Tokyo 134-8630, Japan. arait26d@daiichipharm.co.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Arai
authors.forename: Yasue
authors.initials: Y
authors.lastname: Hosoi
mesh_terms: D000097:Acetonitriles; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006834:Hydrazines; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D010659:Phenylhydrazines; D012680:Sensitivity and Specificity; D013229:Stearic Acids / Q000032:analysis*; D014867:Water
chemical_list: D000097:Acetonitriles; D006834:Hydrazines; D004364:Pharmaceutical Preparations; D010659:Phenylhydrazines; D013229:Stearic Acids; D014867:Water; C060574:2-nitrophenylhydrazine; C031183:stearic acid; C032159:acetonitrile