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Abstract: High-speed counter-current chromatography (HSCCC) technique in semi-preparative scale has been applied to isolate and purify bioactive flavone compounds from the ethanol extract of Glycyrrhiza inflata Bat., a particular plant species of licorice. HSCCC separation was performed with a two-phase solvent system composed of n-hexane–chloroform–methanol–water (5:6:3:2, v/v) by eluting the lower mobile phase at a flow rate of 1.8ml/min and a revolution speed of 800rpm. Purification was performed with a two-phase solvent system composed of n-hexane–chloroform–methanol–water (1.5:6:3:2, v/v) by eluting the lower mobile phase at a flow-rate of 1.5ml/min and a revolution speed of 800rpm. Two major flavone peaks: inflacoumarin A and licochalcone A were collected and the respective yields of the peaks amount to 6mg (8.6%, w/w) and 8mg (11.4%, w/w) from 70mg of the crude extract sample. The purities of inflacoumarin A and licochalcone A reached 99.6% and 99.1%, respectively, after a sequential purification run. The structures of inflacoumarin A and licochalcone A were positively confirmed by 1H NMR and 13C NMR, 1H–13C-COSY, UV, FT-IR and electron ionization MS analyses. [Copyright &y& Elsevier]

Abstract: In this paper, we proposed an approach using a multi-walled carbon nanotubes (MWCNTs)/Nafion composite coating as a working electrode for the electrochemically enhanced solid-phase microextraction (EE-SPME) of charged compounds. Suitable negative and positive potentials were applied to enhance the extraction of cationic (protonated amines) and anionic compounds (deprotonated carboxylic acids) in aqueous solutions, respectively. Compared to the direct SPME mode (DI-SPME) (without applying potential), the EE-SPME presented more effective and selective extraction of charged analytes primarily via electrophoresis and complementary charge interaction. The experimental parameters relating to extraction efficiency of the EE-SPME such as applied potentials, extraction time, ionic strength, sample pH were studied and optimized. The linear dynamic range of developed EE-SPME-GC for the selected amines spanned three orders of magnitude (0.005–1μgmL−1) with R 2 larger than 0.9933, and the limits of detection were in the range of 0.048–0.070ngmL−1. All of these characteristics demonstrate that the proposed MWCNTs/Nafion EE-SPME is an efficient, flexible and versatile sampling and extraction tool which is ideally suited for use with chromatographic methods. [Copyright &y& Elsevier]

Abstract: A versatile, relatively selective, chemically and mechanically robust solid-phase microextraction (SPME) fiber based on methacrylic acid–trimethylolpropanetrimethacrylate (MAA/TRIM) co-polymers was developed in a simple way and directly coupled with gas chromatography. Thus, using a glass capillary as a “mold”, MAA/TRIM co-polymers were immobilized on a stainless steel wire base as a novel coating for SPME. The extraction performance of the MAA/TRIM-coated fiber was evaluated in detail using four triazines as model compounds, and several typical and important species of chemical compounds including opioids, xanthic alkaloids and phenoxyacetic acid herbicides were selected as additional examples to further illustrate the extraction mechanism and applicability of the fiber. The fiber showed high extraction efficiency for highly functionalized molecules (typically containing multiple amino, hydroxy, carbonyl and carboxy groups) via a hydrogen-bonding extraction mechanism. The maximum extraction ability and selectivity of the fiber could be obtained only in non-polar (aprotic) organic solvents, which are effective for the hydrogen-bonding interaction. The inherent chemical stability of MAA/TRIM co-polymers and the mechanical strength of the stainless steel wire as the fiber support made the MAA/TRIM-coated fiber highly durable in practical use. [Copyright &y& Elsevier]

Abstract: A ceramic/carbon composite was developed and applied as a novel coating for solid-phase microextraction (SPME). The ceramic/carbon coating exhibited several good properties for SPME, such as high extraction quantities and enhanced thermal and organic solvent stability. Under scanning electron microscopy (SEM), the tightly attached coating layer on stainless steel wire revealed excellent mechanical characteristics. Single fiber and fiber-to-fiber reproducibility were less than 6.9 and 9.5%, respectively. The effects of extraction and desorption parameters such as extraction time, stirring rate, ionic strength, and desorption temperature and desorption time on the extraction/desorption efficiency were investigated and optimized. Coupled to gas chromatography with a flame thermionic detector, the optimized SPME method was applied to the analysis of organophosphorus pesticides (OPPs) in aqueous samples. The calibration curves were linear from 0.05 to 200ngmL−1 for fenchlorphos, pirimiphos-methyl, chlorpyrifos, ethion and from 0.2 to 200ngmL−1 for quinalphos, and the limits of detection were between 5.2 and 34.6ngL−1. The recovery of the OPPs spiked in real water samples at 5ngmL−1 ranged from 86.2 to 103.4% and the relative standard deviations were less than 8.5%. [Copyright &y& Elsevier]

Abstract: The biodegradation of the organophosphorus insecticide methyl parathion (MP) in aqueous environment by bacteria isolated from river sediment has been studied. Two species of bacteria which show strong MP degradation ability are identified as Shewanella and Vibrio parahaemolyticus. The biodegradation of MP proceeded rapidly with the formation of a series of intermediate products, which were analyzed using a combination of GC/MS and HPLC/ESI-TOFMS techniques. The major products tentatively identified include a series of reduced products of MP. Results demonstrate that the coupling of TOFMS to HPLC enhances further the capability of LC–MS in the identification of polar organic species in complex environmental samples. Degradation pathways leading to the formation of these products are proposed which involves first the reduction of nitro to amino group in MP, followed by combination with some intrinsic matters of bacteria. The mechanism and products from biodegradation are quite different from those of photocatalytic process for which the main intermediates included methyl paraoxon and 4-nitrophenol. [Copyright &y& Elsevier]

Abstract: Glycyrrhizic acid (GA) and licorice flavonoids (LF) are the two classes of bioactive components in licorice with known pharmacological effects. But long-term excessive intake of GA may cause sodium retention and hypertension. In this study, the performance and adsorption characteristics of four widely used macroporous resins for the separation of deglycyrrhizinated, flavonoids enriched licorice has been critically evaluated. The sorption and desorption properties of LF and GA on macroporous resins including XDA-1, LSA-10, D101 and LSA-20 have been compared. The adsorption capacity was found to depend strongly on the pH of the feed solution. XDA-1 offers much higher adsorption capacity for GA and LF than other resins, and its adsorption data fit the best to the Freundlich isotherm. XDA-1 also shows much higher adsorption affinity towards LF than that of GA based on calculated results from the measured adsorption isotherms. Dynamic adsorption and desorption experiments have been carried out on a XDA-1 resin packed column to obtain optimal parameters for separating GA and LF. An enriched LF extract (about 21.9% purity) free of GA, and an enriched GA extract with 66% purity can be separated from crude licorice extract in one run. [Copyright &y& Elsevier]