title: Graphene oxide for solid-phase extraction of bioactive phenolic acids.
abstract: A solid-phase extraction (SPE) method for the efficient analysis of trace phenolic acids (PAs, caffeic acid, ferulic acid, protocatechuic acid, cinnamic acid) in urine was established. In this work, a graphene oxide (GO) coating was grafted onto pure silica to be investigated as SPE material. The prepared GO surface had a layered and wrinkled structure that was rough and well organized, which could provide more open adsorption sites. Owing to its hydrophilicity and polarity, GO showed higher extraction efficiency toward PAs than reduced GO did, in agreement with the theoretical calculation results performed by Gaussian 09 software. The adsorption mechanism of PAs on GO@Sil was also investigated through static state and kinetic state adsorption experiments, which showed a monolayer surface adsorption. Extraction capacity of the as-prepared material was optimized using the response surface methodology. Under the optimized conditions, the as-established method provided wide linearity range (2-50 μg L-1for protocatechuic acid and 1-50 μg L-1for caffeic acid, ferulic acid, and cinnamic acid) and low limits of detection (0.25-1 μg L-1). Finally, the established method was applied for the analysis of urine from two healthy volunteers. The results indicate that the prepared material is a practical, cost-effective medium for the extraction and determination of phenolic acids in complex matrices. Graphical Abstract A graphene oxide coating was grafted onto pure silica as the SPE material for the extraction of phenolic acids in urines and the extraction mechanism was also mainly investigated.
authors.affiliation: CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu, 730000, China.|Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Xiudan
authors.initials: X
authors.lastname: Hou
authors.affiliation: CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu, 730000, China.
authors.forename: Xusheng
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, 200000, China.
authors.forename: Yingxin
authors.initials: Y
authors.lastname: Sun
authors.affiliation: CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu, 730000, China. wanglc@licp.cas.cn.
authors.forename: Licheng
authors.initials: L
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, Gansu, 730000, China. guoyong@licp.cas.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Guo
mesh_terms: D000327:Adsorption; D002109:Caffeic Acids / Q000302:isolation & purification* / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002934:Cinnamates / Q000302:isolation & purification* / Q000652:urine; D003373:Coumaric Acids / Q000302:isolation & purification* / Q000652:urine; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D062385:Hydroxybenzoates / Q000302:isolation & purification* / Q000652:urine; D057230:Limit of Detection; D010087:Oxides / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods*
chemical_list: D002109:Caffeic Acids; D002934:Cinnamates; D003373:Coumaric Acids; D062385:Hydroxybenzoates; D010087:Oxides; C029010:cinnamic acid; C009091:protocatechuic acid; D012822:Silicon Dioxide; D006108:Graphite; C004999:ferulic acid; C017616:phenolic acid; C040048:caffeic acid
keywords: Adsorption mechanism; Graphene oxide; Phenolic acid; Response surface methodology; Solid-phase extraction