Determination of capsaicinoids in topical cream by liquid-liquid extraction and liquid chromatography

A reversed-phase liquid chromatography (LC) method has been developed, optimised and validated for the separation and quantitation of capsaicin (CP) and dihydrocapsaicin (DHCP) in a topical cream formulation. Sample preparation involves liquid-liquid extraction prior to LC analysis. The method uses a Hypersil C-18 BDS, 5 mum, 250 x 4.6 mm I.D. column maintained at 35 degreesC. The mobile phase comprises methanol, water, acetonitrile (ACN) and acetic acid (47:42: 10: 1, v/v/v/v) at a flow rate of 1.0 ml/min. Robustness was evaluated by performing a central composite face-centred design (CCF) experiment. The method shows good selectivity, linearity, sensitivity and repeatability. The conditions allow the separation and quantitation of CP and DHCP without interference from the other substances contained in the cream. (C) 2002 Elsevier Science B.V. All rights reserved.