Journal of Separation Science

Công bố khoa học tiêu biểu

* Dữ liệu chỉ mang tính chất tham khảo

Sắp xếp:  
Analysis of pesticides residues in environmental water samples using multiwalled carbon nanotubes dispersive solid‐phase extraction
Journal of Separation Science - Tập 36 Số 3 - Trang 556-563 - 2013
Miguel Ángel González‐Curbelo, Antonio V. Herrera‐Herrera, Javier Hernández‐Borges, Miguel Ángel Rodríguez‐Delgado
In this manuscript, a dispersive SPE method based on the use of multiwalled carbon nanotubes has been developed for the determination of 15 organophosphorus pesticides residues including some of their metabolites (disulfoton sulfoxide, ethoprophos, cadusafos, dimethoate, terbufos, disulfoton, chlorpyrifos‐methyl, malaoxon, fenitrothion, pirimiphos‐methyl, malathion, chlorpyrifos, terbufos sulfone, disulfoton sulfone, and fensulfothion) from real environmental waters (run‐off, mineral and tap water) by GC with nitrogen phosphorus detection. Factors that affect the enrichment efficiency such as sample volume, multiwalled carbon nanotubes amount, and volume of eluent were studied. The optimized method was validated in terms of matrix‐matched calibration, recovery, precision, and accuracy for the three analyzed samples. In this last case, the developed Student´s t test demonstrated that there were no significant differences between real and spiked concentrations. Optimum dispersive SPE conditions (extraction of 200 mL of water, pH 6.0, with 130 mg of multiwalled carbon nanotubes, elution with 25 mL of dichloromethane for run‐off and tap water and 30 mL for mineral water) allowed the quantitative extraction of analytes at levels lower than the maximum residues limits legislated by the European Union, with LODs between 1.16 and 93.6 ng/L. Absolute recovery values achieved were in the range of 67–107% (RSD values <10.1%).
Simultaneous separation and identification of limonoids from citrus using liquid chromatography‐collision‐induced dissociation mass spectra
Journal of Separation Science - Tập 34 Số 1 - Trang 2-10 - 2011
G.K. Jayaprakasha, Deepak V. Dandekar, Shane E. Tichy, Bhimanagouda S. Patil
AbstractLimonoids are considered as potential cancer chemopreventive agents and are widely distributed in the Citrus genus as aglycones and glucosides. In the present study, reversed‐phase HPLC coupled with CID mass spectra was developed for the simultaneous separation and identification of aglycones and glucosides of limonoids from citrus. Five aglycones such as limonin, deacetyl nomilin, ichangin, isolimonoic acid and nomilin were identified by positive ion CID MS/MS, whereas five glucosides, viz. limonin glucoside, isoobacunoic acid glucoside, obacunone glucoside, deacetyl nomilinic acid glucoside and nomilinic acid glucoside were analyzed by negative ion CID mass spectra. The developed method was successfully applied to complex citrus samples for the separation and identification of aglycones and glucosides. Citrus seeds were extracted with methanol and partially purified and analyzed by LC‐CID mass spectra. The separation was achieved by C‐18 column; eight limonoids were identified by comparing the retention times and mass spectral fragmentation. To the best of our knowledge, this is the first report on the identification of citrus limonoids using CID technique.
Preparative isolation and purification of three flavonoid glycosides from <i>Taraxacum mongolicum</i> by high‐speed counter‐current chromatography
Journal of Separation Science - Tập 31 Số 4 - Trang 683-688 - 2008
Shuyun Shi, Yuping Zhang, Yu Zhao, Huang Ke-long
AbstractA preparative high‐speed counter‐current chromatography (HSCCC) was successively applied to purify three flavonoid glycosides from the aerial part of Taraxacum mongolicum, a traditional Chinese medicine. Subsequent UV, MS, and NMR analyses have led to the characterization of three flavonoid glycosides including two new compounds isoetin‐7‐O‐β‐D‐glucopyranosyl‐2′‐O‐α‐L‐arabinopyranoside and isoetin‐7‐O‐β‐D‐glucopyranosyl‐2′‐O‐α‐D‐glucopyranoside, and a known compound, isoetin‐7‐O‐β‐D‐glucopyranosyl‐2′‐O‐α‐D‐xyloypyranoside, which were first isolated from T. mongolicum. The two‐phase solvent system composed of ethyl acetate/n‐butanol/water (2:1:3, v/v/v) was performed in HSCCC. Consequently, a total of 25.7 mg isoetin‐7‐O‐β‐D‐glucopyranosyl‐2′‐O‐α‐L‐arabinopyranoside, 19.1 mg isoetin‐7‐O‐β‐D‐glucopyranosyl‐2′‐O‐α‐D‐glucopyranoside, and 10.6 mg isoetin‐7‐O‐β‐D‐glucopyranosyl‐2′‐O‐α‐D‐xyloypyranoside were obtained with purity of 98.7, 98.3, and 99.1%, respectively, as determined by HPLC from 500 mg enriched extract after cleaning‐up by polyamide resin.
Comparison of enantioseparation of selected benzodiazepine and phenothiazine derivatives on chiral stationary phases based on β‐cyclodextrin and macrocyclic antibiotics
Journal of Separation Science - Tập 26 Số 8 - Trang 661-668 - 2003
Eva Tesařová, Zuzana Bosáková
AbstractEnantioselective separation of some phenothiazine and benzodiazepine derivatives was studied on six different chiral stationary phases (CSPs) in HPLC. Selected CSPs, with respect to the structure of the separated compounds, were either based on β‐cyclodextrin chiral selectors – underivatized β‐cyclodextrin and hydroxypropyl ether β‐cyclodextrin, or on macrocyclic antibiotics – vancomycin, teicoplanin, teicoplanin aglycone, and ristocetin A. Measurements were carried out in a reversed‐phase separation mode. The influence of mobile phase composition on retention and enantioseparation was studied. Benzodiazepines could be enantioresolved with almost all the chiral stationary phases used, except for the vancomycin‐bonded CSP. Peak coalescence of oxazepam and lorazepam was observed if separation was carried out at laboratory temperature. Reduced temperature was required in some instances in order to avoid the on‐column racemization. Separation systems composed of teicoplanin‐bonded CSP and buffer‐methanolic or pure methanolic mobile phases were shown to be suitable even for preparative purposes due to high resolution values of the enantiomers. Enantioseparation of phenothiazine derivatives was more difficult to achieve but it was successful, at least partly, also with both types of the CSPs used (except for levomepromazine).
Simultaneous determination of 12 active components in the roots of<i>Pulsatilla chinensis</i>using tissue-smashing extraction with liquid chromatography and mass spectrometry
Journal of Separation Science - Tập 40 Số 6 - Trang 1283-1292 - 2017
Miaomiao Jin, Wen-dan Zhang, Yan-mei Xu, Yingfeng Du, Qian Sun, Wei Guo, Liang Cao, Huijun Xu
Determination of 12 pueraria components by high‐performance liquid chromatography‐mass spectrometry
Journal of Separation Science - Tập 28 Số 14 - Trang 1785-1795 - 2005
Ching‐Che Lin, Chuan‐I. Wu, Shuenn‐Jyi Sheu
AbstractPuerariae radix, a commonly used Chinese herb drug derived from the dried root of legume plant, contains a series of isoflavones as its chief pharmacologically active constituents. Using 12 pueraria components as markers, an LC‐UV‐MS method requiring less than 60 min, was developed for estimating the quality of pueraria samples within 60 min. Extracts were analyzed using a Cosmosil 5C18‐MS column, by gradient elution with an aqueous solution of acetic acid and methanol–ACN at a flow‐rate of 1.0 mL/min. Peaks were detected at 254 nm and each peak was identified by LC/MS. The reproducibilities (RSD) of this proposed method, on the basis of peak‐area ratios from six replicate injections, were 0.93–1.42% (intraday) and 1.05–1.63% (interday) at a detection limit of 0.12–0.78 μg/mL. Most of the markers used in this study can be classified, respectively, into three major categories, namely, isoflavones, O‐glycosidic isoflavones, and C‐glycosidic isoflavones. The structures of the compounds were determined from LC‐MS fragmentation data and data from the literature.
<i>Conus ventricosus </i>venom peptides profiling by HPLC‐MS: A new insight in the intraspecific variation
Journal of Separation Science - Tập 31 Số 3 - Trang 488-498 - 2008
Cristina Romeo, Laura Di Francesco, Marco Oliverio, Paola Palazzo, Gabriella Raybaudi Massilia, Paolo Ascenzi, Fabio Polticelli, Maria Eugenia Schininà
AbstractConus is a genus of predatory marine gastropods that poison the prey with a complex mixture of compounds active on muscle and nerve cells. An individual cone snail's venom contains a mixture of pharmacological agents, mostly short, structurally constrained peptides. This study is focused on the composition of the venom employed by Conus ventricosus Gmelin, 1791, a worm‐hunting cone snail living in the Mediterranean Sea. For this purpose, LC coupled to MS techniques has been successfully used to establish qualitative and quantitative differences in conopeptides from minute amounts of venom ducts. We were able to prove variability in the venom conopeptide complement, possibly related to different trophic habits of the species in the Mediterranean Sea. Moreover, the information‐rich MS techniques enabled us to identify two novel C. ventricosus peptides, here named Conotoxin‐Vn and α‐Conotoxin‐Vn. On the basis of the structural data collected so far, we suggest that Conotoxin‐Vn is a conopeptide belonging to the ω‐family that recognizes calcium channels through a specific pharmacophore. Similarly, molecular modeling data suggest that α‐Conotoxin‐Vn should represent a competitive antagonist of neuronal nicotinic acetylcholine receptors (nAChRs).
Chromatography in characterization of polysaccharides from medicinal plants and fungi
Journal of Separation Science - Tập 36 Số 1 - Trang 1-19 - 2013
Dejun Hu, Kit‐Leong Cheong, Jing Wang, Shaoping Li
Polysaccharides isolated from medicinal plants and fungi exhibit multiple pharmacological activities. The biological activities of polysaccharides depend on their chemical characteristics. However, characterization of polysaccahrides is a challenge because of their complicated structure and macromolecular mass. In this review, chromatography in characterization of polysaccharides, including physicochemical characterization (purity, molecular mass, and distribution), structural characterization (constituent monosaccharide composition and the ratio, the features of glycosidic linkages), and fingerprint of polysaccharides (acidic and enzymatic hydrolysates), from medicinal plants and fungi were reviewed and discussed according to the publications collected in Web of Science since 2007. The perspective for characterization of polysaccharides has also been described.
Behaviour of carbamate pesticides in gas chromatography and their determination with solid‐phase extraction and solid‐phase microextraction as preconcentration steps
Journal of Separation Science - Tập 28 Số 16 - Trang 2130-2138 - 2005
R. Carabias-Martı́nez, César García‐Hermida, Encarnación Rodríguez‐Gonzalo, Luis Ruano‐Miguel
AbstractThis work reports a study of the chromatographic behaviour of seven carbamate pesticides (aldicarb, carbetamide, propoxur, carbofuran, carbaryl, methiocarb, and pirimicarb) by gas chromatography‐mass spectrometry (GC‐MS). Variables such as injector temperature, solvent, injection mode, and the degree of ageing of the chromatographic column were studied. One of the aims of this work was to achieve a controlled decomposition of carbamates by a solid‐phase microextraction (SPME) preconcentration step with a polyacrylate fibre in order to obtain reproducible chromatographic signals of the degradation products. Optimisation of the SPME process was accomplished by means of experimental design. Several methods using ultrapure water were developed with different preconcentration configurations: SPME‐GC‐MS, SPE followed by SPME‐GC‐MS, and SPE plus GC‐MS. For all the pesticides studied, method detection limit (MDL) values below 0.1 μg L–1 were reached in at least one of the proposed configurations.
Pressurized liquid extraction followed by LC‐ESI/MS for analysis of four chromones in Radix Saposhnikoviae
Journal of Separation Science - Tập 33 Số 17-18 - Trang 2881-2887 - 2010
Wei Li, Zi Wang, Li Chen, Jing Zhang, Li‐Kun Han, Jingang Hou, Yinan Zheng
AbstractAn efficient pressurized liquid extraction (PLE) technique was employed in extracting chromones from the roots of Saposhnikovia divaricata (Radix Saposhnikoviae). Chromones were quantified and analyzed by LC‐ESI/MS. The PLE procedure was optimized, validated and compared with the other conventional extraction techniques. PLE gained the best result due to the highest extraction efficiency within the shortest extraction time. The optimal conditions of PLE were employing 50% ethanol as the extraction solvent at a temperature of 140°C and an extraction pressure of 1500 psi, using one extraction cycle with a static extraction time of 8 min. A good LC separation was achieved using a Hypersil ODS2 column and methanol/water as the mobile phase at a flow rate of 0.8 mL/min. MS coupling with an ESI interface in the positive ion mode was used as the detection technique. This is the first report on combining PLE with LC‐ESI/MS for the extraction and quantification of chromones in Radix Saposhnikoviae. The elaborated PLE method also provided a good alternative for the chromone extraction from other plant substances.
Tổng số: 127   
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 10