title: Extraction and determination of morphine in compound liquorice using an aqueous two-phase system of poly(ethylene glycol)/K2HPO4 coupled with HPLC.
abstract: An aqueous two-phase system (ATPS) of poly(ethylene glycol) (PEG)/K(2)HPO(4) coupled with high performance liquid chromatography (HPLC) method was developed for the separation and determination of morphine in compound liquorice. Morphine and its analogs were used as model compounds to investigate influence of various factors on extraction behaviors of ATPS, such as the types and concentrations of salts, PEG molecular mass, temperature and pH. It was observed that the types of salt had much influence on extraction efficiencies of morphine and its analogs. The results indicated that hydrophobic force cooperating with hydrogen bond interaction between analytes and phases played important role in extraction process. In the optimal system of containing 0.5g PEG2000 and 1.5g K(2)HPO(4), the recoveries of the spiked standards for the analytes were all 91.7-100.3% with relative standard deviation of 1.0-3.0%. Morphine in compound liquorice was determined by the proposed method and the results were consistent with those of LC-MS method. Compared with conventional liquid-liquid extraction or solid-phase extraction, this extraction method can be completed in one operation and is low-cost. Since the entire extraction process is organic solvent-free, this new technique is environmental friendly.
authors.affiliation: The Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Institute of Analytical Chemistry, College of Chemistry, Peking University, Beijing 100871, China.
authors.forename: Shehong
authors.initials: S
authors.lastname: Li
authors.forename: Chiyang
authors.initials: C
authors.lastname: He
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.forename: Daobing
authors.initials: D
authors.lastname: Li
authors.forename: Zheng
authors.initials: Z
authors.lastname: Chen
authors.forename: Huwei
authors.initials: H
authors.lastname: Liu
authors.forename: Kean
authors.initials: K
authors.lastname: Li
authors.forename: Feng
authors.initials: F
authors.lastname: Liu