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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 206: 104-111, 2019 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-30099310

RESUMO

The potential energy surface for the reaction of O(3P) with CH2 = CHCH2F has been studied at the CCSD(T)//M06-2X level of theory. Three different reaction entrances were revealed, namely, terminal-C addition, central-C addition, and H(or F)-abstraction, leading to CH2OCHCH2F (IM1), CH2CHOCH2F (IM2) and HO + C3H4I (OF + C3H5), respectively. The corresponding activation barriers are 3.04 (TS1), 3.71 (TS2), 7.06 (h-TS1), 12.68 (h-TS2), 14.04 (h-TS3) and 63.58 kcal/mol (F-TS1) kcal/mol. Several conceivable decomposition and isomerization channels were also examined for IM1 and IM2. The total and individual rate constants were calculated by using Multichannel RRKM and TST theory over a wide range of temperatures (200-3000 K) and pressures(10-14-1014 Torr).The branching ratios indicate that IM1 is the major product at 200-800 K. The production of P1 (CH2FCHCHO + H)via H-elimination from IM1 becomes dominant at high temperatures.

2.
Talanta ; 142: 228-34, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26003716

RESUMO

A novel procedure for selective extraction of malachite green (MG) from fish samples was set up by using magnetic molecularly imprinted polymers (MMIP) as the solid phase extraction material followed by electrochemiluminescence (ECL) determination. MMIP was prepared by using Fe3O4 magnetite as magnetic component, MG as template molecule, methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent. MMIP was characterized by SEM, TEM, FT-IR, VSM and XRD. Leucomalachite green (LMG) was oxidized in situ to MG by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). And then MMIP was successfully used to selectively enrich MG from fish samples. Adsorbed MG was desorbed and determined by ECL. Under the optimal conditions, calibration curve was good linear in the range of 0.29-290 µg/kg and the limit of detection (LOD) was 7.3 ng/kg (S/N=3). The recoveries of MMIP extraction were 77.1-101.2%. In addition, MMIP could be regenerated. To the best of our knowledge, MMIP coupling with ECL quenching of Ru(bpy)3(2+)/TPA for the determination of MG has not yet been developed.


Assuntos
Peixes , Contaminação de Alimentos/análise , Corantes de Rosanilina/análise , Adsorção , Animais , Anti-Infecciosos Locais/análise , Anti-Infecciosos Locais/química , Corantes/análise , Corantes/química , Fungicidas Industriais/análise , Fungicidas Industriais/química , Fenômenos Magnéticos , Nanopartículas de Magnetita/química , Impressão Molecular , Compostos Organometálicos/química , Propilaminas/química , Corantes de Rosanilina/química , Dióxido de Silício/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
3.
Talanta ; 115: 457-61, 2013 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-24054618

RESUMO

A novel sensor based on thiol-porphyrin mixed monolayer-tethered polyaniline (PANI) with intercalating fullerenols was applied to sensitively detect m-dinitrobenzene (m-DNB) by differential pulse voltammetry (DPV). The thiolated polyaniline was examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrode modification of thiol-porphyrin mixed monolayer-tethered polyaniline with intercalating fullerenols exhibited a higher analytical sensitivity versus that of thiol-porphyrin mixed monolayer-tethered polyaniline, because the fullerenols in mixed monolayer could improve the preconcentration efficiencies of m-DNB. Under optimum conditions, the linear calibration curves ranged from 0.029 to 10,000 nmol L(-1) for m-DNB, with a limit of detection (S/N=3) of 9.72 pmol L(-1).


Assuntos
Compostos de Anilina/química , Dinitrobenzenos/análise , Fulerenos/química , Porfirinas/química , Compostos de Sulfidrila/química , Calibragem , Técnicas Eletroquímicas , Eletrodos , Limite de Detecção
4.
Talanta ; 110: 15-20, 2013 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-23618169

RESUMO

In this paper, coenzyme Q10 (Ubiquinone, CoQ10) was used for the first time as a transducer to construct electrochemical biosensor for effectively detecting γ-L-glutamyl-L-cysteinyl-glycine (glutathione, GSH). CoQ10 modified electrode was fabricated by attaching its gel mixed with multi-walled carbon nanotubes (MWNTs)/ionic liquid (IL). In the optimum conditions, based on the increasing of reduction peak current of CoQ10 caused by GSH through voltammetric technology, it was found that the peak current of CoQ10 was linear with the concentration of GSH in the range from 4.0×10(-9) to 2.0×10(-7)mol L(-1) at the pH 7.00, and the limit of detection was 3.2×10(-10)mol L(-1) (S/N=3). The results revealed that this method could be used to determine GSH in actual blood samples with the superiority of excellent selectivity, high stability and sensitivity. The strategy explored here might provide a new pathway to design novel multi-function transducers for detecting GSH, which has unique characteristic and potential application in the fields of sensor and medical diagnosis.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas/instrumentação , Glutationa/análise , Ubiquinona/química , Humanos , Limite de Detecção
5.
Talanta ; 106: 174-80, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-23598113

RESUMO

Efficient and stable quenching of electrochemiluminescence of Ru(bpy)3(2+)/TPA by malachite green(MG) and crystal violet(CV) at the glass carbon (GC) electrode is reported. A novel quenching mechanism has been proposed. Resonance energy transfer from the excited-state luminophore Ru(bpy)3(2+*) to MG/CV and dynamic quenching are suggested as the mechanism for quenching ECL. The quenching mechanism is discussed in detail based on UV-visible absorption spectra, cyclic voltammograms, ECL curves and fluorescence methods. MG shows more efficient quenching than CV. Moreover, the quenched ECL intensity versus the concentration of MG and CV are linear over the concentration ranges of 8 × 10(-10)-8 × 10(-7)M and 3.46 × 10(-9)-5.5 × 10(-7)M, respectively. The corresponding limit of detection (LOD) was 1.0 × 10(-10)M for MG and 1.1 × 10(-10)M for CV (S/N=3).

6.
Acta Crystallogr Sect E Struct Rep Online ; 69(Pt 2): o216, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23424497

RESUMO

The title compound, C(28)H(38)Br(2)N(2), is centrosymmetric with the mid-point of the central C-C bond of the butyl group located on an inversion center. The terminal benzene ring is approximately perpendicular to the central 1,4-diaza-butadiene mean plane [dihedral angle = 78.23 (3)°]. No hydrogen bonding or aromatic stacking is observed in the crystal structure.

7.
Analyst ; 137(6): 1416-20, 2012 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-22290275

RESUMO

Electrochemiluminescence (ECL) of Ru(bpy)(3)(2+) using metabolites of catecholamines: homovanillic acid (HVA) and vanillylmandelic acid (VMA) as co-reactants were investigated in aqueous solution for the first time. When HVA and VMA were co-existent in the buffer solution containing Ru(bpy)(3)(2+), ECL peaks were observed at a potential corresponding to the oxidation of Ru(bpy)(3)(2+), and the ECL intensity was increased noticeably when the concentrations of HVA and VMA were at lower levels. The linear calibration range was from 8.0 × 10(-5) to 1.0 × 10(-9) M for HVA and VMA. The detection limit (S/N = 3) of HVA and VMA was 4.0 × 10(-10) M. The formation of the excited state Ru(bpy)(3)(2+*) was confirmed to result from the reaction between Ru(bpy)(3)(3+) and the intermediates of HVA or VMA radicals. Moreover, it was found that the ECL intensity was quenched significantly when the concentrations of HVA and VMA were relatively higher. The mechanism of self-quenching processes involved in the Ru(bpy)(3)(2+)-HVA and -VMA ECL systems are proposed in this study.


Assuntos
Catecolaminas/metabolismo , Eletroquímica/métodos , Ácido Homovanílico/química , Medições Luminescentes/métodos , Compostos Organometálicos/química , Ácido Vanilmandélico/química , Tampões (Química) , Catecolaminas/química , Eletroquímica/instrumentação , Ácido Homovanílico/metabolismo , Medições Luminescentes/instrumentação , Oxirredução , Ácido Vanilmandélico/metabolismo
8.
Yao Xue Xue Bao ; 46(4): 443-6, 2011 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-21751498

RESUMO

Nonaqueous capillary electrophoresis is used for the determination of the contents of diosgenin and ruscogenin in Radix Ophiopogonis. The operating buffer was composed of 20 mmol x L(-1) Na2B4O7-HCl (pH 7.61) in 70% methanol. The applied voltage was 25 kV and detection potential was at +0.70 V. With these conditions, the components were successfully separated. The content of diosgenin in Radix Ophiopogonis was 0.018 mg x g(-1) and ruscogenin was 0.008 mg x g(-1). The average recoveries of diosgenin and ruscogenin were 102% and 99.2%, respectively. A new method of the quality control of diosgenin and ruscogenin in Radix Ophiopogonis is provided.


Assuntos
Diosgenina/análise , Eletroforese Capilar/métodos , Ophiopogon/química , Plantas Medicinais/química , Espirostanos/análise , Raízes de Plantas/química , Controle de Qualidade
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