Use of Solid‐Phase Extraction for Improving HPLC Assays of Triterpene Glycosides in Gotu Kola (Centella asiatica), Parthenolide in Feverfew (Tanacetum parthenium), and Valerenic Acids in Valerian (Valeriana officinalis)

References

• http://www.nsfina.org/ (Accessed: August 2004 ).
   Google Scholar
• Anderson , M. L. and Burney , D. P. 1998 . Validation of sample preparation procedures for botanical analysis . J. AOAC Int. , 81 ( 5 ) : 1005 – 1010 .
   Web of Science ®Google Scholar
• Inamdar , P. K. , Yeole , R. D. , Ghogare , A. B. and de Souza , N. J. 1996 . Determination of biologically active constituents in Centella asiatica . J. Chromatogr. A , 742 : 127 – 130 .
   Web of Science ®Google Scholar
• Günther , B. and Wagner , H. 1996 . Quantitative determination of triterpenes in extracts and phytopreparations of Centella asiatica (L.) . Urban. Phytomed. , 3 ( 1 ) : 59 – 65 .
   PubMed Web of Science ®Google Scholar
• Brinkhaus , B. , Lindner , M. , Schuppan , D. and Hahn , E. G. 2000 . Chemical, pharmacological and clinical profile of the east asian medical plant Centella asiatica . Phytomed. , 7 ( 5 ) : 427 – 448 .
   PubMed Web of Science ®Google Scholar
• Zhou , J. Z.Q. , Kou , X. and Stevenson , D. 1999 . Rapid extraction and high‐performance liquid chromatographic determination of parthenolide in feverfew (Tanacetum parthenium) . J. Agric. Food Chem. , 47 : 1018 – 1022 .
   PubMed Web of Science ®Google Scholar
• Bos , R. , Woerdenbag , H. J. , Hendriks , H. , Zwaving , J. H. , De Smet , P. A.G.M. , Tittel , G. , Wikström , H. V. and Scheffer , J. J.C. 1996 . Analytical aspects of phytotherapeutic valerian preparations . Phytochem. Anal. , 7 : 143 – 151 .
   Web of Science ®Google Scholar
• Woerdenbag , H. J. , Bos , R. and Scheffer , J. J.C. 1997 . “ Valerian: Quality assurance of the crude drug and its preparations ” . In Valerian, The Genus Valeriana Edited by: Houghton , P. J. 101 – 128 . Amsterdam : Harwood Academic Publishers .
   Google Scholar
• Glowniak , K. , Zgórka , G. and Kozyra , M. 1996 . Solid‐phase extraction and reversed‐phase high‐performance liquid chromatography of free phenolic acids in some Echinacea species . J. Chromatogr. A , 730 : 25 – 29 .
   Web of Science ®Google Scholar
• Schieffer , G. W. 2000 . Validated HPLC method for caffeic‐acid derivatives and alkylamides in Echinacea solid‐dosage forms using a single extraction procedure . JANA , : 67 – 81 .
   Google Scholar
• Bauer , R. , Khan , I. A. and Wagner , H. 1987 . Analysis and standardization of medicinal and phytopreparations by HPLC and other chromatographic methods. 8. Echinacea. Detection of Adulteration of Echinacea purpurea Moench with Parthenium integrifolium . L. Dtsch. Apoth. Ztg. , 127 ( 25 ) : 1325 – 1330 .
   Google Scholar
• Cardone , M. J. , Palermo , P. J. and Sybrandt , L. B. 1980 . Potential error in single‐point‐ratio calculations based on linear calibration curves with a significant intercept . Anal. Chem. , 52 : 1187 – 1191 .
   Web of Science ®Google Scholar