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Abstract: Benzo[a]pyrene, a common environmental pollutant, can be metabolized into reactive anti-benzo[a]pyrene diol epoxide (anti-BPDE), which predominantly binds to deoxyguanine in DNA and forms four stereoisomeric adducts. To characterize the stereochemistry of these adduct isomers, preparation of single adducted deoxyguanosine (dG) is required for efficient enantiomeric analysis. Here, we demonstrate an improved method for preparation, identification, and analysis of four BPDE-adducted dGs, including (+)-trans-, (−)-trans-, (+)-cis-, and (−)-cis-anti-BPDE-N 2 -dG. These stereoisomerically adducted nucleosides were first synthesized by a direct reaction of (±)-anti-BPDE with dG, followed by optimized solid-phase extraction (SPE) and HPLC purification. The reaction of (±)-anti-BPDE and dG displayed a yield as high as 45%. The developed preparation method does not require any enzymatic digestion. Based on highly efficient separation achieved by optimization of stationary phase and mobile phase, LC-UV–MS/MS and LC-diode array detection (DAD)-fluorescence detection (FL) methods were established for characterization and analysis of the four stereoisomeric anti-BPDE-dGs. The established LC-DAD-FL method may provide characterization and analysis of four stereoisomeric anti-BPDE-dGs and two interfering anti-BPDE tetrols by taking advantage of their distinct fluorescence quenching. [Copyright &y& Elsevier]

Abstract: A high-performance liquid chromatography (HPLC) method with evaporative light scattering detection (ELSD) was applied for simultaneous determination of stachyose, sucrose and raffinose in Chinese artichoke (Stachys Sieboldii Miq.). Carbohydrates were separated on a Bondapak NH2 column using a ternary solvent mixture of methanol–acetonitrile–water (55:25:20, v/v/v) as mobile phase. Two different crafts (method 1 and method 2) for extraction and purification of stachyose in Chinese artichoke tubers were detailed and evaluated. Method 1 can meet the purpose of quantification and method 2 is appropriate for the purpose of purification. The content of stachyose in dry tubers was determined to be 236.0mg/g (from method 1) and the purity of the extracted stachyose flour was calculated to be 87.34% (from method 2), respectively. The analytical method fulfills all the standard requirements of linearity, accuracy and precision. Therefore, it is suitable for purification and routine quantification of stachyose in Chinese artichoke. [Copyright &y& Elsevier]

Abstract: A monolithic molecularly imprinted polymer (monolithic MIP) was designed and prepared for chiral separation of nateglinide and its l-enantiomer. The enantiomers were rapidly separated on this novel monolithic MIP based chiral stationary phase (MIP-CSP), whereas the enantioseparation was not obtained on the non-imprinted polymer (NIP). Chiral recognition was found to be dependent on the stereo structures and the arrangement of functional groups of the imprinted molecule and the cavities on MIP. Thermodynamic data (ΔΔH and ΔΔS) obtained by Van’t Hoff plots revealed an enthalpy-controlled enantioseparation. The binding capacity was evaluated by frontal analysis. Monolithic nateglinide-MIP had an effective number of binding sites B t =41.15μmolg−1 with a dissociation constant of K d =7.40mM. The morphological characteristics of the monolithic MIP were investigated by pore analysis and scanning electron microscope (SEM). Results showed that both mesopores and macropores were formed in the monolith. Over all, this study presents a new and practical possibility for providing high rates of mass transfer, fast separations and high efficiencies without the pressure constraints of the traditional bulk molecularly imprinted polymers, through the monolithic MIPs. [Copyright &y& Elsevier]

Abstract: A weak ion exchange monolithic column prepared by modifying the GMA–MAA–EDMA (glycidyl methacrylate–methacrylic acid–ethylene glycol dimethacrylate) monoliths with ethylenediamine was applied to remove matrix compounds in biological fluid. Using this monolithic column, on-line clean-up and screening of oxacillin and cloxacillin in human urine and plasma samples had been investigated. Chromatography was performed by reversed-phase HPLC on a C18 column with ultraviolet detection at 225nm. Results showed that the ion exchange monolithic column could be used for deproteinization and retaining oxacillin and cloxacillin in human urine and plasma, which provided a simple and fast method for assaying drugs in human urine and plasma. [Copyright &y& Elsevier]