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  • Author or Editor: G. J. Yang x
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A simple and sensitive method of high-performance liquid chromatography with fluorescence detection (HPLC-FLD) was developed for the determination of icariin in capsules by precolumn chelation with aluminum. In order to obtain a stable fluorescence signal, the reaction conditions of the fluorescent chelation complex between icariin and aluminum were investigated in detail. Chromatography was carried out on an Agilent Zorbax Extend C18 column (150 mm × 4.6 mm, 5.0 μm) using methanol as mobile phase at a flow rate of 1.0 mL min−1. The excitation and emission wavelengths were set at 430 and 480 nm, respectively. At optimum conditions, the calibration curve was linear in the concentration range from 0.010 to 100.0 μg mL−1 with the limit of detection of 3.5 ng mL−1 (S/N = 3). A comprehensive method was validated for precision and accuracy. The method described here has been successfully applied for the determination of the icariin content in a capsule with satisfactory results.

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Silica-gel column chromatography and preparative reversed-phase high-performance liquid chromatography (RP-HPLC) were sequentially employed for the isolation of two antioxidants including gallic acid and methyl gallate from Folium Toonea Sinensis. An RP-HPLC-UV method was then developed and validated to rapidly determine their content in this herb with ethyl gallate as internal standard. The quantitation was performed on an XBridge Shield RP18 column (150 mm × 4.6 mm, 5 μm) under 40°C. The mobile phase consisting of acetonitrile and 0.1% formic acid aqueous solution was driven at 1.0 mL min−1 under gradient elution, and 270 nm was selected to monitor the separation. To evaluate the fitness for purpose of the method and to investigate the difference in the content of analytes among different samples, the leaves collected from five production sites were analyzed. The newly established method is suitable for routine analysis of gallic acid and methyl gallate in the herb and, hence, can assist in its quality assessment. It was also found that not only the content of two antioxidants but also the ratio varied significantly among different geographical origins. In addition, three samples from Yantai, Zumadian, and Zhenjiang were distinguished as they have a much higher content ratio than the other two.

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