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1.
Mikrochim Acta ; 186(10): 675, 2019 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-31494752

RESUMO

Nitrogen-doped carbon dots (N-CDs) with fluorescence excitation/emission maxima at 365/450 nm were prepared by a one-step hydrothermal approach. The dots possess remarkable photostability, fluorescence blinking and good biocompatibility, and this favors utilization in stochastic optical reconstruction microscopy (STORM). A spatial resolution down to ~60 nm was achieved when imaging HeLa cells using 647-nm laser excitation. This opens new possibilities for various super-resolution techniques based on stochastic optical switching. The remarkable optical properties of the N-CDs also enable them to be applied as invisible security ink for use in patterning, information storage and anti-counterfeiting. Further, it is found that the fluorescence of the N-CDs can be quenched by curcumin with high efficiency due to a combination of inner filter effect and static quenching. Based on this, a fluorometric assay with a detection limit of 21 ng mL-1 was developed for the determination of curcumin. Graphical abstract Schematic representation of the applications of N-doped carbon dots (N-CDs). Curcumin quenches the fluorescence of N-CDs with high efficiency. The remarkable optical properties of the N-CDs enable them to be applied in fluorescent ink, cell imaging and stochastic optical reconstruction microscopy (STORM).

2.
J Chromatogr A ; 1605: 460372, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31402106

RESUMO

The present work describes the preparation of two ionic liquid and carboxyl acid silane reagents via photo-initiated thiol-ene click chemistry that have been bonded to silica to afford two mixed-mode stationary phases (Sil-C4Im-C9Co and Sil-C9Im-C4Co). The two stationary phases provided satisfactory retention repeatability and efficiencies. The influence of acetonitrile content, salt concentration and pH of the mobile phase was investigated to clarify the retention properties of the prepared stationary phases. The results showed that the prepared Sil-C4Im-C9Co and Sil-C9Im-C4Co undergo multiple interactions with solutes under different chromatographic conditions. The retention mechanisms were further studied by the linear energy solvation relationship and Van't Hoff plots. Finally, the stationary phases were employed to separate hydrophobic solutes (alkylbenzenes and polycyclic aromatic hydrocarbons) under reversed phase liquid chromatography (RPLC) mode, hydrophilic solutes (carboxylic acids, nucleosides and bases) under hydrophilic interaction liquid chromatography (HILIC) mode and inorganic anions under ion-exchange chromatography (IEC) mode, providing excellent performance and varying selectivity when compared with a commercial column. The bonding method in this work is feasible and the prepared stationary phases are promising when employed in RPLC/HILIC/IEC mixed-mode chromatography applications.

3.
Analyst ; 144(17): 5186-5192, 2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31343643

RESUMO

A reliable, highly sensitive and highly selective method of high performance liquid chromatography associated with resonance Rayleigh scattering (HPLC-RRS) was developed to detect three cytokinins, namely, 6-benzylaminopurine (BA), kinetin (KT) and zeatin (ZT). In this work, Pd(ii) is added into the system to form ternary ion association complexes for the first time, which results in a lower limit of detection and extends the application of HPLC-RRS. The experimental conditions were optimized. In order to investigate the reaction mechanism, the ternary ion association complexes were characterized by ultraviolet-visible spectrophotometry, dynamic light scattering, scanning electron microscopy and density functional theory calculations. In a HAc-NaAc buffer solution (pH = 4.1), a ternary complex of cytokinin : Pd(ii) : EryB (1 : 1 : 2) was formed. The detection limits (S/N = 3) of BA, KT, and ZT were 0.9, 1.5 and 2.3 ng mL-1, respectively. In addition, this method was applied for the simultaneous detection of cytokinins in real samples with satisfactory results.


Assuntos
Citocininas/análise , Compostos de Benzil/análise , Cromatografia Líquida de Alta Pressão , Difusão Dinâmica da Luz , Eritrosina/análise , Cinetina/análise , Limite de Detecção , Purinas/análise , Soja/química , Zeatina/análise
4.
Analyst ; 144(10): 3307-3313, 2019 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-30968873

RESUMO

A quadruple-channel fluorescent sensor array based on label-free carbon dots (CDs) was fabricated to detect and discriminate a series of tetracyclines (TCs), including chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TC) and doxycycline (DOX). Blue-emitting carbon dots (B-CDs) and green-emitting carbon dots (G-CDs) were prepared to serve as four sensing elements. When the TCs were directly mixed with CDs, the fluorescence quenching phenomenon appeared. Since different TCs exhibited different affinities for sensing elements, the sensor array displays a distinct fluorescence pattern of the fluorescence intensity variation (F0 - F)/F0 for each of these TCs, which is further analyzed by principal component analysis (PCA). The present fluorescent sensor array has the capacity to differentiate TCs at a low concentration of 1 µM. Meanwhile, quantitative detection with a lower limit (0.30 µM) for TCs could be achieved by applying a single element. Moreover, a high accuracy (100%) examination of unknown samples is acquired. Finally, the fluorescent sensor array performs well in distinguishing binary mixtures and could also recognize TCs in milk.


Assuntos
Antibacterianos/análise , Carbono/química , Corantes Fluorescentes/química , Pontos Quânticos/química , Tetraciclinas/análise , Animais , Antibacterianos/classificação , Fluorescência , Contaminação de Alimentos/análise , Limite de Detecção , Leite/química , Análise de Componente Principal , Espectrometria de Fluorescência/métodos , Tetraciclinas/classificação
5.
Luminescence ; 33(7): 1171-1179, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30112790

RESUMO

A highly sensitive and selective method of high performance liquid chromatography (HPLC) combined with resonance Rayleigh scattering (RRS) spectra was developed for the detection of three antihistamine drugs, including pyrilamine (PY), carbinoxamine (CAR) and tripelennamine (TRI). The three antihistamines were separated by a C18 column. The mobile phase contained 25% acetonitrile (ACN) and 75% phosphate buffered solution (pH 3.2) with the flow rate of 0.4 ml min-1 . In medium of Britton-Robinson (BR) buffer solution (pH 4.6), the PY, CAR and TRI separated by HPLC and then reacted with Erythrosine B (EryB), forming 1:1 ion-association complexes, which led to significant signal enhancement of RRS spectra. The RRS spectra was detected at the wavelength λex =λem = 370 nm. The calibration curves of PY, CAR and TRI were linear in the range from 0.02 to 25 µg ml-1 , and the detection limit [signal-to-noise ratio (S/N) = 3] were 3.38, 4.48 and 5.50 ng ml-1 , respectively. In addition, under the optimum experiment condition, the reaction mechanism and the reasons for RRS enhancement were investigated in this work. The developed method was applied to the simultaneous detection of three antihistamines in water samples with satisfying results.

6.
Anal Bioanal Chem ; 410(23): 5941-5950, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29968107

RESUMO

4-Hydroxy-D-phenylglycine was modified with methacrylic anhydride and then immobilized on silica through thiol-initiated surface polymerization; the prepared material was applied as stationary phase for HPLC. The obtained stationary phase was characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analysis. The chromatographic performance of the packed column was evaluated in reversed-phase liquid chromatograph (RPLC) and hydrophilic interaction liquid chromatograph (HILIC) mode; this column has shown excellent selectivity to both the hydrophobic and hydrophilic solutes. The selectivity towards polycyclic aromatic hydrocarbons relative to that towards alkylbenzenes exhibited by the prepared column was higher than the corresponding selectivity exhibited by commercial C18 column, which could be explained by electronic π-π interaction between phenylglycine and electron-rich aromatic rings. On the other hand, the prepared column has also shown better selectivity for polar compounds, which was based on the multiple interaction and retention mechanisms. It was also used to separate sulfonamides and organic acid compared with a commercial C18 and HILIC column; the results show its great chromatographic performance with distinctive selectivity. All the results indicated the prepared column had potential application in a wide range.


Assuntos
Cromatografia de Fase Reversa/métodos , Glicina/análogos & derivados , Ácidos/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Glicina/química , Interações Hidrofóbicas e Hidrofílicas , Polimerização , Dióxido de Silício/química , Compostos de Sulfidrila/química , Sulfonamidas/isolamento & purificação
7.
Luminescence ; 33(2): 417-424, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29271102

RESUMO

Herein, a highly selective high-performance liquid chromatography (HPLC) coupled with resonance Rayleigh scattering (RRS) method was developed to detect gatifloxacin (GFLX) and sparfloxacin (SPLX). GFLX and SPLX were first separated by HPLC, then, in pH 4.4 Britton-Robinson (BR) buffer medium, protonic quaternary ammonia cation of GFLX and SPLX reacted with erythrosine (ERY) to form 1:1 ion-association complexes, which resulted in a significant enhancement of RRS signal. The experimental conditions of HPLC and post-column RRS have been investigated, including detection wavelength, flow rate, pH, reacting tube length and reaction temperature. Reaction mechanism were studied in detail by calculating the distribution fraction. The maximum RRS signals for GFLX and SPLX were recorded at λex  = λem  = 330 nm. The detection limits were 3.8 ng ml-1 for GFLX and 17.5 ng ml-1 for SPLX at a signal-to-noise ratio of 3. The developed method was successfully applied to the determination of GFLX and SPLX in water samples. Recoveries from spiked water samples were 97.56-98.85%.


Assuntos
Antibacterianos/análise , Cromatografia Líquida de Alta Pressão/métodos , Eritrosina/química , Fluoroquinolonas/análise , Cromatografia Líquida de Alta Pressão/instrumentação , Gatifloxacina , Poluentes Químicos da Água/análise
8.
Artigo em Inglês | MEDLINE | ID: mdl-28122287

RESUMO

A highly sensitive detection approach of resonance Rayleigh scattering spectra (RRS) is firstly applied to analyzing nootropic drugs including piracetam (PIR) and oxiracetam (OXI). In HCl-NaAc buffer solution (pH=3.0), the OXI chelated with palladium (II) to form the chelate cation [Pd2·OXI]2+, and then reacted with Congo red (CGR) by virtue of electrostatic attraction and hydrophobic force to form binary complex [Pd2·OXI]. CGR2, which could result in the great enhancement of RRS. The resonance Rayleigh scattering signal was recorded at λex=λem=375nm. This mixture complex not only has higher RRS, but also makes contribution to significant increase of fluorescence, and the same phenomena also were discovered in PIR. The enhanced RRS intensity is in proportion to the PIR and OXI concentration in the range of 0.03-3.0µgmL-1, and the detection limit (DL) of RRS method for PIR and OXI is 2.3ngmL-1 and 9.7ngmL-1. In addition, the DL of fluorescence method for PIR and OXI is 8.4µgmL-1 and 19.5µgmL-1. Obviously, the RRS is the highly sensitive method, and the recoveries of the two kinds of nootropic drugs were range from 100.4% to 101.8.0% with RSD (n=5) from 1.1% to 3.1% by RRS method. This paper not only investigated the optimum conditions for detecting nootropics with using RRS method, but also focused on the reasons for enhancing RRS intensity and the reaction mechanism, which in order to firm and contract the resultant. Finally, The RRS method has been applied to detect nootropic drugs in human urine samples with satisfactory results.


Assuntos
Quelantes/química , Vermelho Congo/química , Nootrópicos/química , Paládio/química , Espalhamento de Radiação , Concentração de Íons de Hidrogênio , Limite de Detecção , Conformação Molecular , Concentração Osmolar , Piracetam/química , Pirrolidinas/química , Espectrometria de Fluorescência
9.
Luminescence ; 32(1): 4-10, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27145989

RESUMO

A highly selective and sensitive method of reversed phase high-performance liquid chromatography (RP-HPLC) coupled with resonance Rayleigh scattering (RRS) was developed for the determination of procaine, bupivacaine and tetracaine. Separation of three local anaesthetics was achieved at 35 °C on a C18 column. The mobile phase was 30: 70 (v/v) acetonitrile/triethylamine-phosphoric acid buffer (pH 2.9) at flow rate of 0.3 mL/min. The RRS detection was conducted by taking advantage of the strong RRS enhancement of the local anaesthetics with erythrosine reaction in an acidic medium. Under optimum conditions, the limit of detection (S/N = 3) values were in the range of 2.4-11.2 ng/mL. Recoveries from spiked human urine samples were 95.8%-104.5%. The proposed method applied to the determination of local anaesthetics in human urine achieved satisfactory results. In addition, the mechanism of the reaction is fully discussed. Copyright © 2016 John Wiley & Sons, Ltd.


Assuntos
Anestésicos Locais/urina , Bupivacaína/urina , Procaína/urina , Tetracaína/urina , Cromatografia Líquida de Alta Pressão , Humanos , Espalhamento de Radiação , Espectrometria de Fluorescência
10.
Anal Bioanal Chem ; 408(19): 5247-59, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27209593

RESUMO

A novel, highly selective, and sensitive resonance light scattering (RLS) detection approach coupled with high performance liquid chromatography (HPLC) was researched and developed for the synchronous analysis of three kinds of benzimidazole anthelmintics, including mebendazole (MBZ), albendazole (ABZ), and fenbendazole (FBZ) for the first time. In the pH range of 3.5-3.7 Britton-Robinson buffer medium, three kinds of anthelmintics, which were separated by HPLC, reacted with eosin Y (EY) to form 1:1 ion-association complexes, resulting in significantly enhanced RLS signals and the maximum peak located at 335 nm. The enhanced RLS intensity was in proportion to the MBZ, ABZ, and FBZ concentration in the range 0.2-25, 0.2-23, and 0.15-20 µg/mL, respectively. The limit of detection was in the range of 0.064-0.16 µg/mL. In addition, human urine was determined to validate the proposed method by spiked samples and real urine samples. Satisfactory results were obtained by HPLC-RLS method. Graphical Abstract The diagram mechanism of generating resonance between emitted light and scattered light.


Assuntos
Anti-Helmínticos/química , Benzimidazóis/química , Cromatografia Líquida de Alta Pressão/métodos , Amarelo de Eosina-(YS)/química , Refratometria/métodos , Urina/química , Anti-Helmínticos/análise , Benzimidazóis/análise , Sítios de Ligação , Corantes Fluorescentes/química , Humanos , Concentração de Íons de Hidrogênio , Luz , Ligação Proteica , Mapeamento de Interação de Proteínas , Reprodutibilidade dos Testes , Espalhamento de Radiação , Sensibilidade e Especificidade
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 136 Pt B: 1181-7, 2015 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-25456660

RESUMO

A reliable and versatile high performance liquid chromatography coupled with resonance Rayleigh scattering method was established for the determination of three fluoroquinolones, including levofloxacin, norfloxacin and enrofloxacin in water sample and human urine sample. In pH 4.4-4.6 Britton-Robinson buffer medium, the fluoroquinolones separated by high performance liquid chromatography could react with erythrosine to form 1:1 ion-association complexes, which could make contributions to the great enhancement of RRS. The resonance Rayleigh scattering signal was recorded at λex=λem=330 nm. The resonance Rayleigh scattering spectral characteristics of the drugs and the experimental conditions such as pH, detection wavelength, erythrosine concentration, flow rate, the length of reaction tube were studied. Quantum chemistry calculation, Fourier transform infrared spectroscopy and absorption spectroscopy were used to discuss the reaction mechanism. The recoveries of samples added standard ranged from 97.53% to 102.00%, and the relative standard deviation was below 4.64%. The limit of detection (S/N=3) of 0.05-0.12 µg mL(-1) was reached, and the linear regression coefficients were all above 0.999. The proposed method was proved as a simple, low cost and high sensitivity method.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Fluoroquinolonas/urina , Luz , Espalhamento de Radiação , Enrofloxacina , Eritrosina/química , Fluoroquinolonas/análise , Fluoroquinolonas/química , Concentração de Íons de Hidrogênio , Levofloxacino/química , Levofloxacino/urina , Modelos Moleculares , Norfloxacino/química , Norfloxacino/urina , Teoria Quântica , Padrões de Referência , Espectroscopia de Infravermelho com Transformada de Fourier
12.
Analyst ; 138(17): 4818-22, 2013 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-23817314

RESUMO

In the present study, an ultrasensitive electrochemical aptasensor for the simultaneous detection of thrombin (TB) and ochratoxin A (OTA) was fabricated by using exonuclease-catalyzed target recycling and DNA concatemers for signal amplification. The previously hybridized double-stranded DNAs (SH-cTBA/TBA and SH-cOBA/OBA) were self-assembled on a gold electrode. In the presence of targets, the formation of aptamer-target complexes would lead to not only the dissociation of aptamers (TBA and OBA) from the double-stranded DNAs but also the transformation of the complementary DNAs (SH-cTBA and SH-cOBA) into hairpin structures. Subsequently, owing to employment of RecJf exonuclease, which is a single-stranded DNA-specific exonuclease to selectively digest the appointed DNAs (TBA and OBA), the targets could be liberated from the aptamer-target complexes for recycling of the analytes. Thereafter, probe DNAs (T1 and T2) were employed to hybridize with SH-cTBA and SH-cOBA respectively to provide primers for the concatemer reaction. After that, when four auxiliary DNA strands S1, anthraquinone-2-carboxylic acid (AQ)-labeled S2, S3, S4, as well as hemin were introduced, extended dsDNA polymers with lots of AQ moieties and hemin-G-quadruplex complexes could form on the electrode surface. Then, based on the signal of the AQ and hemin-G-quadruplex complex, an electrochemical aptasensor for the simultaneous detection of TB and OTA was successfully fabricated.


Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Biocatálise , Técnicas Biossensoriais/métodos , DNA/química , Exodesoxirribonucleases/metabolismo , Ocratoxinas/análise , Trombina/análise , Animais , DNA/metabolismo , Eletroquímica , Ocratoxinas/metabolismo , Trombina/metabolismo , Fatores de Tempo
13.
Anal Chim Acta ; 706(2): 199-204, 2011 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-22023853

RESUMO

In view of the fact that many substances generally exhibit very little ultraviolet absorbance and the absence of native fluorescence, a new strategy with simple instrumentation and excellent analytical performance combining high performance liquid chromatography (HPLC) with resonance Rayleigh scattering (RRS) was developed. It was validated for the quantification of aminoglycosides (AGs). This fact was also carefully calculated by quantum chemistry. However, the sensitivity was probably limited by the volume of flow-through cell. Therefore, the result calls for a suitable one to ensure optimal RRS signal. Interestingly, when serum or urine samples of analytes were analyzed by this method, they were all well resolved without any interference, which would hold a new perspective to be applied in the determination of substances in biological matrix.


Assuntos
Aminoglicosídeos/análise , Cromatografia Líquida de Alta Pressão/métodos , Luz , Espalhamento de Radiação , Aminoglicosídeos/sangue , Aminoglicosídeos/química , Aminoglicosídeos/urina , Humanos , Indicadores e Reagentes/química , Modelos Moleculares , Conformação Molecular
14.
J Sep Sci ; 34(21): 2997-3003, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21913328

RESUMO

The dynamics of a novel method coupling high-performance liquid chromatography (HPLC) with resonance Rayleigh scattering (RRS) is presented in the paper. The method was employed in the detection of fluoroquinolones (FQs) of urine samples from healthy human beings, by forming ion-association complexes between the components separated from HPLC and [Ce(OH)(3) ](+) as the molecular recognition probe. The RRS signal was measured at λ(ex) =λ(em) =365 nm. It was applied to detect three FQs and obtained satisfactory results. The RRS spectral characteristics of the analytes and the kinetics of flow rate, proportion of organic phase, reaction time and the aggregation level of ion-association complexes were investigated, which provided a new basis for the development of the hyphenated techniques. It was established that the presence of HPLC-RRS would open up a new field in the determination of analytes in the absence of UV or fluorescence.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Fluoroquinolonas/urina , Espalhamento de Radiação , Análise Espectral/métodos , Termodinâmica , Cromatografia Líquida de Alta Pressão/instrumentação , Humanos , Valores de Referência , Análise Espectral/instrumentação
15.
Se Pu ; 27(6): 794-8, 2009 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-20352933

RESUMO

A new, simple and sensitive method based on pre-column derivatization by reversed-phase high performance liquid chromatography (HPLC) is described for the separation and quantification of netilmicin in plasma, using 9-fluorenylmethyl chloroformate (FMOC-Cl) as the derivatization reagent. Its pharmacokinetics is also presented. The derivatization modes and chromatographic conditions were optimized. The separation was performed on an Agilent ZORBAX Eclipse XDB-C8 column (150 mm x 4.6 mm, 5 microm) with a mixture of water-acetonitrile (15:85, v/v) as mobile phase and the flow rate was 1.0 mL/min. The excitation wavelength was 265 nm and the emission wavelength was 315 nm. The linear range was 0.045-8.88 mg/L and the correlation coefficient (r) was 0.9993. The limit of detection (LOD) (S/N = 3) was about 0.01 mg/L, and the limit of quantification was 0.03 mg/L (3LOD) for netilmicin. The relative standard deviation was less than 3% for intra-day assay (n = 5) and 3.5% for inter-day assay (n = 5) and the relative recovery was in the range of 96.62%-100.84% (n = 3). The plasma volume of 30 microL was sufficient for the determination of netilmicin. The method provides a reliable bioanalytical methodology to carry out netilmicin pharmacokinetics in rat plasma.


Assuntos
Cromatografia de Fase Reversa/métodos , Netilmicina/sangue , Animais , Netilmicina/farmacocinética , Ratos
16.
Anal Chim Acta ; 630(1): 101-6, 2008 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-19068331

RESUMO

A new reversed-phase high performance liquid chromatography with resonance Rayleigh scattering detection (HPLC-RRS) was developed for simultaneous separation and determination of four tetracycline antibiotics (TCs). A good chromatographic separation among the compounds was achieved using a Synergi Fusion-RP column (150 mm x 4.6 mm; 4 microm) and a mobile phase consisting of methanol-acetonitrile-oxalic acid (5mM) at the flow rate of 0.8 mLmin(-1). Column temperature was 30 degrees C. The RRS signal was detected at lambda(ex)=lambda(em)=370 nm. The recoveries of sample added standard ranged from 95.3% to 103.5%, and the relative standard deviation was below 2.79%. A detection limit of 2.12-5.12 microgmL(-1) was reached and a linear range was found between peak height and concentration in the range of 10.36-518.0 microgmL(-1) for oxytetracycline (OTC), 12.11-605.5 microgmL(-1) for tetracycline (TC), 11.79-589.5 microgmL(-1) for chlortetracycline (CTC) and 10.32-516.0 microgmL(-1) for doxycycline (DC). The linear regression coefficients were all above 0.999. The method has been applied successfully to the determination of OTC, TC, CTC, DC in pharmaceutical formulations and in honey. The method was simple, rapid and showed a better linear relation and high repeatability.


Assuntos
Antibacterianos/análise , Cromatografia Líquida de Alta Pressão/métodos , Tetraciclinas/análise , Clortetraciclina/análise , Cromatografia Líquida/métodos , Doxiciclina/análise , Resíduos de Drogas/análise , Mel/análise , Indicadores e Reagentes , Análise de Regressão , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrometria de Fluorescência/métodos , Tetraciclina/análise
17.
Anal Sci ; 22(10): 1301-5, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17038766

RESUMO

In a diluted H2SO4 solution, Hg(II) reacts with halide anions X- (including Cl-, Br- and I-) to form anionic complexes [HgX4]2- that can further react with berberine to form ion-association complexes of [Ber]2[HgX4]. As a result, the absorption spectra change, their maximum absorption wavelengths are at 230 nm for [Ber]2[HgCl4], 278 nm for [Ber]2[HgBr4] and 300 nm for [Ber]2[HgI4]. However, among the three complexes, only [Ber]2[HgI4] can lead to distinctly enhanced resonance Rayleigh scattering (RRS), and a new RRS spectrum appears. The maximum RRS wavelength is located at 397 nm, and the RRS intensity is proportional to the concentration of berberine in the range of 0-2.5 microg mL-1. The optimum conditions, the influence factors for the reaction and the effects of coexisting substances have been investigated. A new, simple and fast RRS method for the determination of berberine based on the ion-association reaction of [HgI4]2- with Ber+ was developed. The method has high sensitivity and good selectivity; the detection limit for berberine (3 sigma/K) is 7.22 ng mL-1. The method can be applied to the determination of berberine in some Chinese patent drug and the extracts of Coptis Chinensis. Furthermore, the mechanism of the reaction and the reasons for RRS enhancement have been discussed.


Assuntos
Berberina/farmacologia , Técnicas de Química Analítica/métodos , Mercúrio/química , Espectrofotometria/instrumentação , Xenônio/química , Absorção , Química Orgânica/métodos , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Íons , Medicina Tradicional Chinesa , Modelos Químicos , Espalhamento de Radiação , Solventes , Espectrofotometria/métodos , Água
18.
Anal Sci ; 21(3): 259-62, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15790109

RESUMO

An RP-HPLC method for the separation and determination of aluminium(III), vanadium(V), iron(III), copper(II) and nickel(II) with CALKS (Chromazol KS) and PAR ([4-(2-pyridylazo)resorcinol]) chelating on a YWG-ODS column was developed. A mixture of methanol-tetrahydrofuran(THF)-water (60:5:35 v/v) containing 0.2 mol/L LiCl, 5 x 10(-5) mol/L CALKS, 5 x 10(-5) mol/L PAR and acetate buffer solution (pH 4.9) was selected as mobile phase. The method has high sensitivity, with the detection limits being 6 ng/mL for aluminium(III), 3.5 ng/mL for vanadium(V), 10.4 ng/mL for iron(III), 6.3 ng/mL for copper(II) and 8.7 ng/mL for nickel(II). It also has good selectivity, so that most foreign metal ions do not interfere under the optimum conditions. The method can be applied to the simultaneous determination of trace amounts of aluminium, vanadium, iron, copper and nickel in rice and flour samples.

19.
Se Pu ; 20(6): 550-3, 2002 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-12683006

RESUMO

A method for the separation and determination of theanine in tea leaves has been developed, based on inhibited chemiluminescence of cobalt-catalyzed luminol-H2O2 reaction by theanine. Separations were performed on a YWG-C18 column using a mobile phase of 0.01 mol.L-1 sodium acetate-acetic acid buffer at pH 5.5 at a flow rate of 0.8 mL.min-1. The optimum concentrations of Co2+, luminol, and H2O2 were 2 micrograms.L-1, 0.25 mmol.L-1, and 0.5 mmol.L-1, respectively. Under the conditions mentioned above, the relative peak area (Y) of inhibited chemiluminescence of theanine was linear with the concentration (X) of theanine in the range of 0.2 g.L-1-5.0 g.L-1 and its linear regression equation was Y = 33,862 x + 1.0605 (r = 0.9983). The average recovery was 97.82% with a RSD of 2.16%.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Glutamatos/análise , Chá/química , Catálise , Cobalto , Medições Luminescentes , Luminol , Folhas de Planta/química
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