title: [Determination of quercetin and kaempferol in Polygonum aviculare by HPLC].
abstract: OBJECTIVE
  To develop a high performance liquid chromatographic method for the simultaneous determination of quercetin and kaempferol in Polygonum aviculare.
  
  
  METHODS
  The optimized method was achieved for the separation and detection of quercetin and kaempferol using Kromasil C18 column (4.6 mm x 250 mm, 5 microm) as the stationary phase, methanol-0.1% aqueous phosphoric acid solution (65:35) as the mobile phase at a flow rate of 1.0 mL x min(-1), 366 nm as the detection wavelength. The main factors, extraction solvent extraction time, hydrolysis tine, temperature and hydrochloric acid concentration, which influenced the sample extraction and hydrolysis procedure, were intensively explored.
  
  
  RESULTS
  Methanol and 65% methanol were chosen as the extracting solvent for the free compounds and for the total compounds, respectively. The optimized hydrolysis procedure was that the sample was hydrolyzed 1.0 h with 4.0 mol x L(-1) hydrochloric acid at 80 degrees C. Quercetin and kaempferol showed good relationship at the range of 0.58-362 mg x L(-1) and 0.51-320 mg x L(-1), respectively. Both of the correlation coefficients of the calibration curves were 0.999 9. The detection limits of quercetin and kaempferol were 0.03 mg x L(-1) and 0.02 mg x L(-1) at a signal-to-noise ratio of 3, respectively. The average recoveries of quercetin and kaempferol were 99.7% and 99.0% with relative standard derivation (RSD) of 1.7% and 3.9%.
  
  
  CONCLUSIONS
  The results showed that the method is simple, accurate and repeatable and it is suitable for quality control of Polygonum aviculare.
authors.affiliation: Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Chen
authors.forename: Yanping
authors.initials: Y
authors.lastname: Shi
mesh_terms: D000975:Antioxidants / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004365:Drugs, Chinese Herbal / Q000032:analysis / Q000737:chemistry*; D044949:Kaempferols / Q000032:analysis*; D010936:Plant Extracts / Q000737:chemistry; D028502:Polygonum / Q000737:chemistry*; D011794:Quercetin / Q000032:analysis*
chemical_list: D000975:Antioxidants; D004365:Drugs, Chinese Herbal; D044949:Kaempferols; D010936:Plant Extracts; C006552:kaempferol; D011794:Quercetin