Micelle-mediated extraction and cloud-point preconcentration of osthole and imperatorin from Cnidium monnieri with analysis by high performance liquid chromatography

A new method based on micelle-mediated extraction and cloud-point preconcentration was developed for the separation and determination of hydrophobic compounds osthole and imperatorin from Cnidium monnieri by high performance liquid chromatography with photodiode array detection. The non-ionic surfactant C13E8 (Genapol X-080) was chosen as the extract solvent. Various experimental conditions were investigated to evaluate and optimize the extraction and preconcentration process. The chromatographic separation was accomplished on a Zorbax SB-C18 analytical column (150 turn x 4.6 mm i.d., 5 mu m particle diameter) maintained at 30 degrees C and detected by UV absorption at 320 nm. The gradient elution was achieved with a mobile phase composed of 0.1% phosphoric acid and acetonitrile at a flow Fate of 1.0 mL min(-1). Under the optimum conditions, the calibration curve for both analytes was linear in the range of 0.52-33.5 mu g mL(-1) with the correlation coefficients greater than 0.9996. The intra-day and inter-day precision (RSD) is below 5.3% and the limits of detection (LOD) for the analytes are 93 and 124 ng mL(-1) (S/N =3). The proposed technique is a low cost, simple and sensitive method with high cleanup effect. Finally, the method was successfully applied to separate and determine osthole and imperatorin from C. mormieri, respectively. (c) 2008 Elsevier B.V. All rights reserved.