title: Solvent effects on focused microwave assisted extraction of polyphenolic acids from Eucommia ulmodies.
abstract: An open microwave-assisted extraction system was used to extract gallic acid, protocatechuic acid, chlorogenic acid and caffeic acid from Eucommia ulmodies. The effect of extraction variables, especially solvent, on the recoveries of these polyphenolic compounds was investigated using factorial design. As extracting solvent for these compounds, methanol produced a higher recovery than pure water. For straight chain alcohol solvents, the lower the carbon number, the higher the recoveries of the polyphenolic acids. The optimal ratio of methanol:water:glacial acetic acid in the solvent mixture used in microwave-assisted extraction was 2:8:0.3 (v/v) and this solvent could be directly used as the mobile phase in HPLC separation without additional intermittent treatment as reported in literature. The extraction under the condition of 50% microwave power and 30 s irradiation at a solvent:sample ratio of 10 (mL/g) was found to be the most advantageous. The repeatability test of extraction and chromatographic analysis was satisfactory for the analysis of these polyphenolic compounds.
authors.affiliation: State Key Laboratory of Chemo/Biological Sensing and Chemometrics, Hunan University, Changsha 410082, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Chen
authors.forename: Lihua
authors.initials: L
authors.lastname: Nie
authors.forename: Shouzhuo
authors.initials: S
authors.lastname: Yao
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D004365:Drugs, Chinese Herbal / Q000737:chemistry; D031283:Eucommiaceae / Q000737:chemistry*; D005419:Flavonoids / Q000302:isolation & purification*; D062385:Hydroxybenzoates / Q000302:isolation & purification*; D008872:Microwaves; D010636:Phenols / Q000302:isolation & purification*; D059808:Polyphenols; D012997:Solvents / Q000737:chemistry
chemical_list: D004365:Drugs, Chinese Herbal; D005419:Flavonoids; D062385:Hydroxybenzoates; D010636:Phenols; D059808:Polyphenols; D012997:Solvents