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63.
Rosa Mª. González-Rodríguez Beatriz Cancho-GrandeJesús Simal-Gándara 《Journal of chromatography. A》2009,1216(32):6033-6042
A gas chromatographic ion trap mass spectrometry (GC-ITMS) method was developed for the determination of 11 new generation fungicides (benalaxyl, benalaxyl-M, boscalid, cyazofamid, famoxadone, fenamidone, fluquinconazole, iprovalicarb, pyraclostrobin, trifloxystrobin and zoxamide) in grapes and wines. Samples were extracted with ethyl acetate:hexane (1:1, v/v) and cleaned-up with graphitized carbon black/primary secondary amine (GCB/PSA) solid-phase extraction (SPE) cartridges using acetonitrile:toluene (3:1, v/v) as eluent. The addition of analyte protectants (3-ethoxy-1,2-propanediol, d-sorbitol and l-gulonic acid γ-lactone) in the final extracts allowed to avoid the matrix-induced response enhancement effect on quantitation process with absolute recoveries ca. 100%. Precision (expressed as relative standard deviation) was lower than 16% for all fungicides. Limits of detection and quantitation were lower than 0.01 mg/kg or mg/L, except for cyazofamid, much smaller in all cases than maximum residue levels (MRLs) established by European Union for grapes and by Switzerland and Italy for wines. The proposed method was applied to determine fungicide residues in three different white grapes for vinification produced in Ribeiro area in Galicia (NW Spain), as well as in their corresponding final wines. 相似文献
64.
Tatiana Visnevschi-Necrasov Sara C. Cunha Eugénia Nunes M. Beatriz P.P. Oliveira 《Journal of chromatography. A》2009,1216(18):3720-3724
A method based on matrix solid-phase dispersion (MSPD) has been developed for the determination of 12 isoflavones in Trifolium pratense L. Dried leaf samples were blended with C18, placed in small columns and isoflavones extracted with dichloromethane–methanol. Analyses were performed by high performance liquid chromatography with diode array detection (HPLC-DAD) with 2-methoxyflavone as internal standard. Several dispersants, eluents and clean-up steps were tested during the optimization of the process in order to obtain the best selectivity and yields. Mean recoveries ranged from 70% to 119%, with relative standard deviations <18%. The limits of detection were between 0.006 mg/l for biochanin A and 0.108 mg/l for daidzin. The performance of the optimized method in real samples was compared with a conventional method based in solid–liquid extraction (SLE). 相似文献
65.
B.S. Santos P.M.A. Farias A. Fontes A.G. Brasil Jr. C.N. Jovino A.G.C. Neto F.D. de Menezes R. Ferreira 《Applied Surface Science》2008,255(3):796-798
Semiconductor nanoparticles in the quantum confinement regime used as biolabels present many advantages over the other chemical species used as fluorophores. They are composed of 2000-6000 atoms rendering a far greater photostability and allowing for long time bioimaging experiments. In this work we present a synthetic route for the obtention of large quantities of highly fluorescent CdSe and CdTe/CdS core-shell nanocrystals based on aqueous colloidal chemistry. The methodologies were optimized and the systems were characterized by optical spectroscopy, transmission electronic microscopy and X-Ray diffractometry. The fluorescent biolabels were tested in live macrophages. 相似文献
66.
Rafael Y. O. Moreira Davi S. B. Brasil Cláudio N. Alves Giselle M. S. P. Guilhon Lourivaldo S. Santos Mara S. P. Arruda Adolfo H. Müller Patrícia S. Barbosa Alcicley S. Abreu Edilene O. Silva Victor M. Rumjanek Jaime Souza Jr. Albérico B. F. da Silva Regina H. de A. Santos 《International journal of quantum chemistry》2008,108(3):513-520
Julocrotine, N‐(2,6‐dioxo‐1‐phenethyl‐piperidin‐3‐yl)‐2‐methyl‐butyramide, is a potent antiproliferative agent against the promastigote and amastigote forms of Leishmania amazonensis (L.). In this work, the crystal structure of Julocrotine was solved by X‐ray diffraction, and its geometrical parameters were compared with theoretical calculations at the B3LYP and HF level of theory. IR and NMR spectra also have been obtained and compared with theoretical calculations. IR absorptions calculated with the B3LYP level of theory employed together with the 6‐311G+(d,p) basis set, are close to those observed experimentally. Theoretical NMR calculations show little deviation from experimental results. The results show that the theory is in accordance with the experimental data. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
67.
Fresco-Cala Beatriz Cárdenas Soledad Herrero-Martínez José Manuel 《Mikrochimica acta》2017,184(6):1863-1871
Microchimica Acta - A copolymer was prepared from glycidyl methacrylate, ethylene glycol dimethacrylate and oxidized single-walled carbon nanohorns via photo-polymerization and used in spin columns... 相似文献
68.
Ashish Kumar Yahya E. Jad Ayman El-Faham Beatriz G. de la Torre Fernando Albericio 《Tetrahedron letters》2017,58(30):2986-2988
Herein, we report the use of γ-valerolactone (GVL) and N-formylmorpholine (NFM) as DMF substitutes in polystyrene based SPPS. The solubility of selected amino acids and coupling reagents were studied in GVL and NFM, followed by their use in the successful synthesis of Aib-enkephalin pentapeptide (H-Tyr-Aib-Aib-Phe-Leu-NH2) and Aib-ACP decapeptide (H-Val-Gln-Aib-Aib-Ile-Asp-Tyr-Ile-Asn-Gly-NH2). 相似文献
69.
Vapor–liquid equilibria (VLE) data at 100 kPa have been determinated for the ternary system cyclohexane + cyclohexene + morpholine and two constituent binary systems cyclohexane + morpholine and cyclohexene + morpholine. The thermodynamic consistency of experimental data has been verified. Both binary systems deviate moderately from ideality without the presence of an azeotrope. The VLE data have been well correlated using local composition models (Wilson, NRTL and UNIQUAC) and have been also predicted with the original UNIFAC. 相似文献
70.
Éder José dos Santos Amanda Beatriz Herrmann Charyane Satie Sato Tatiane Andrade Maranhão Adilson José Curtius 《Microchemical Journal》2010,96(1):27-216
Mercury and lead were determined in an extraction solution applied to compact fluorescent lamps by axial view inductively coupled plasma optical emission spectrometry (ICP OES). The solution contained 50% v/v HNO3 and 10% v/v H2O2. The compact fluorescent lamps were treated by removing the socket and breaking the rest of the lamp inside the solution, followed by placing the mixture in an ultrasonic bath for 1 h. The mixture was filtrated in a coarse paper filter and the resulting extraction slurry was analyzed. The determination of Pb in the slurry required calibration by the analyte addition technique, while for Hg, external calibration was adequate. The quantification limits (10 s, n = 7), for Hg (194.164 nm) and Pb (220.353 nm) were, respectively, 10 and 30 µg per lamp. Analysis of spiked samples demonstrated reasonable accuracy of the method, with recoveries in the range from 99 to 120% for Hg and from 91 to 107% for Pb. Fifteen analyzed samples showed Hg masses per lamp in the range from 1.6 to 27 mg, and six samples were above the limit allowed by the European Community that is 5 mg per compact lamp. The values for Pb were between 0.07 and 0.75 mg per lamp. By filtrating the slurry in a membrane filter, and analyzing the resulting solution, it was found that all Hg was extracted to the liquid phase of the slurry, while a fraction of about 40% m/v of Pb is retained in the solid particles. The lamp cover glass, after extraction of the phosphor layer, was also analyzed for Hg and Pb. The concentration of Hg in the glass is quite low; however, the Pb content is high. 相似文献