Determination of daphnetin in Daphne tangutica and its medicinal preparation by liquid chromatography

A liquid chromatographic (LC) technique coupled with photodiode array (PDA) detection was developed for determining daphnetin in extracts of Daphne tangutica and its medicinal preparation. The optimized method was achieved for the separation and detection of selected constituent using methanol-0.5% phosphonic acid as the mobile phase at a flow rate of 0.8 mL min(-1), and 325 nm as the detection wavelength. Daphnetin showed good linearity in a relatively wide concentration range (r > 0.999). Intra- and inter-assay accuracy and precision were all lower than 5.0%. Sample extracting and purifying procedures were intensively explored. The recovery of the method was 94.8%-105.0% with a relative standard deviation (R.S.D.) of 4.0%. The concentration of daphnetin in D. tangutica from different locations and in its medicinal preparation manufactured by different factories was quite different. The current method may serve as a valuable tool for quality control of D. tangutica and its preparation. (C) 2004 Elsevier B.V. All rights reserved.