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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
381

Enantiomeric Separations using Chiral Counter-Ions

Haglöf, Jakob January 2010 (has links)
This thesis describes the use of chiral counter-ions for the enantiomeric separation of amines in non-aqueous capillary electrophoresis. The investigations have been concentrated on studies of the influence, of the chiral counter-ion, the solvent, the electrolyte and the analyte, on the enantioselective separation. Modified divalent dipeptides have been introduced in capillary electrophoresis for the separation of amino alcohols and chiral resolution of amines. Association constants for the ion-pair between dipeptide and amino alcohol could be utilized for development of separation systems with higher amino alcohol selectivity. Chiral discrimination (ion-pair formation) between the dipeptides and amines are preferably generated in non-aqueous background electrolytes (BGEs). The amount of triethylamine in the BGE determined the dipeptide charge and a divalent dipeptide promoted higher enantioselectivity than a monovalent dipeptide. An N-terminal-end blocking group and glutamic acid at the C-terminal-end of the dipeptide was important for chiral separation of the amines. Chemometric and univariate methods have been employed for evaluation of suitable solvent compositions in the BGE. An experimental design including a single solvent as well as binary, ternary and quaternary mixtures of polar organic solvents, showed that optimal enantioresolution was obtained with an ethanol:methanol 80:20 mixture in the BGE.  Furthermore, water was found to have an adverse influence on enantioselectivity and no enantioresolution was obtained with BGEs containing more than 30 % water. An alkali metal hydroxide added to the BGE affected the chiral separation by competing ion-pair formation with the selector. The electroosmosis was reduced in order of decreasing alkali metal ion solvated radius and became anodic using K, Rb or Cs in ethanolic BGEs. The correlation between the amino alcohol structure and the enantioselectivity was investigated using chemometrics. The obtained models showed that enantioselectivity for the amino alcohols was promoted by e.g. degree of substitution and substituent size on the nitrogen.
382

Determination of monophosphate nucleotides, sulfur-containing amino acids, arsenic species and various oxidation states of iron, vanadium and chromium by capillary electrophoresis inductively coupled plasma mass spectrometry

Yeh, Ching-fen 15 July 2005 (has links)
Capillary electrophoresis (CE) is in comparison with other chromatographic techniques, CE has several advantages such as high resolving power, small sample volume requirement, minimal buffer consumption and high sample throughtput. As a detection technique, inductively coupled plasma mass spectrometry (ICPMS) provides the advantages of low detection limit, multielement detection, and element- and isotope-specific detection capabilities. Therefore, the use of CE as a high resolution separation technique with ICP-MS as a sensitive element specific detector is of growing interest for analytical research. Four studies in our research are described below, respectively. A preliminary study of a modified microconcentric nebulizer (CEI-100, CETAC) as the sample introduction device of capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) for the determination of monophosphate nucleotides is described. The monophosphate nucleotides studied include adenosine 5¡¦-monophosphate (AMP), guanosine 5¡¦-monophosphate (GMP), uridine 5¡¦-monophosphate (UMP) and inosine 5¡¦-monophosphate (IMP). The species studied were well separated using a 70 cm length ¡Ñ 75 £gm id fused silica capillary while the applied voltage was set at -22 kV and a 20 mmol/L ammonium citrate/citric acid buffer (pH 4.0) containing 0.1% m/v cationic polymer (hexadimethrine bromide, Polybrene) was used as the electrophoretic buffer. The electroosmotic flow was reversed by flushing the fused silica capillary with 0.2% m/v Polybrene to accelerate separation. The detection limit of various species studied was in the range of 0.036~0.054 £gg P/mL, which corresponded to the absolute detection limit of 1.1~1.6 pg P based on the injection volume of 30 nl. We determined the concentrations of nucleotides in two IG-enriched monosodium glutamates purchased from the local market. The recovery was in the range of 100~112% for various species, and the concentrations of IMP and GMP in these samples were in the range of 0.15¡V0.18% m/m. Capillary electrophoresis dynamic reaction cellTM inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the determination of sulfur-containing amino acids is described. The sulfur-containing amino acids studied include L-cysteine, L-cystine, DL-homocystine and L-methionine. The species studied were well separated using a 70 cm length ¡Ñ 75 £gm i.d. fused silica capillary while the applied voltage was set at +22 kV and a 10 mmol/L disodium tetraborate buffer (pH 9.8) containing 0.1 mmol/L EDTA and 0.5 mmol/L Triton X-100 was used as the electrophoretic buffer. The sulfur-selective electropherogram was determined at m/z 48 as 32S16O+ by using its reaction with O2 in the reaction cell. The method avoided the effect of polyatomic isobaric interferences at m/z 32 caused by 16O16O+ and 14N18O+ on 32S+ by detecting 32S+ as the oxide ion 32S16O+ at m/z 48, which is less interfered. The detection limit of various species studied was in the range of 0.047~0.058 £gg S/mL, which corresponded to the absolute detection limit of 1.3~1.6 pg S based on the injection volume of 27 nl. We determined the concentrations of selected sulfur-containing amino acids in urine and nutritive complement samples. The recovery was in the range of 92~128% for various species. Capillary electrophoresis-dynamic reaction cell inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the speciation of iron (III/II), vanadium (V/IV) and chromium (VI/III) is described. Two different CE migration modes were employed for separating the six metal ions using pre-capillary complexation. One is counter-electroosmotic mode in which iron (III/II) and vanadium (V/IV) ions were well separated using a 60 cm ¡Ñ 75 £gm i.d. fused silica capillary. The voltage was set at +22 kV and a 15 mmol/L tris(hydroxymethyl)aminomethane (Tris) buffer (pH 8.75) containing 0.5 mmol/L ethylenediaminetetraacetic acid (EDTA) and 0.5 mmol/L ortho-phenanthroline (phen) was used as the electrophoretic buffer. The other is co-electroosmotic mode in which chromium (VI/III) ions were well separated while the applied voltage was set at −22 kV and a 10 mmol/L ammonium citrate buffer (pH 7.7) containing 0.5 mmol/L diethylenetriaminepentaacetic acid (DTPA) and 0.01% polybrene was used as the electrophoretic buffer. The mass spectra were measured at m/z 51, 52 and 56 for V, Cr and Fe, respectively. The interfering polyatomic ions of 35Cl16O+, 40Ar12C+ and 40Ar16O+ on 51V+, 52Cr+ and 56Fe+ determination were reduced in intensity significantly by using NH3 as the reaction cell gas in the DRC. The detection limits were in the range of 0.1~0.5, 0.4~1.3 and 1.2~1.7 £gg/L for V, Cr and Fe, respectively. Applications of the method for the speciation of V, Cr and Fe in wastewater were demonstrated. The recoveries were in the range of 92~120% for various species. A capillary electrophoresis-inductively coupled plasma-mass spectrometric (CE-ICPMS) method for the speciation of six arsenic compounds, namely arsenite [As(III)], arsenate [As(V)], monomethyl arsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine is described. The separation has been achieved on a 70 cm length ¡Ñ 75 £gm ID fused-silica capillary. The electrophoretic buffer used was 15 mmol/L Tris (pH 9.0) containing 15 mmol/L sodium dodecyl sulfate (SDS), while the applied voltage was set at +22 kV. The arsenic species in biological tissues were extracted into 80% v/v methanol-water mixture, put in a closed centrifuge tube and kept in a water bath, using microwaves at 80¢J for 3 min. The extraction efficiencies of individual arsenic species added to the sample at 0.5 mg As/g level were between 96% and 107%, except for As(III), for which it was 89% and 77% for oyster and fish samples, respectively. The detection limits of the species studied were in the range 0.3~0.5 £gg As/L. The procedure has been applied for the speciation analysis of two reference materials, namely dogfish muscle tissue (NRCC DORM-2) and oyster tissue (NIST SRM 1566a), and two real-world samples.
383

Simultaneous Determination of Sulfhydryl and Disulfide Containing Amino Acids by Capillary Electrophoresis with Electrochemical Detection at Au/Hg Microelectrode

Hsu, Kai-Chih 31 August 2005 (has links)
None.
384

Starch microstructure and functional properties in waxy rice (Oryza sativa L.)

Rosa Cuevas Unknown Date (has links)
Rice starch contains two types of glucose polymers, mainly linear amylose and hyper-branched amylopectin. Waxy rice has been characterised by the lack of amylose, the proportion of which being one of the most important parameters measured for rice quality. Germplasm collection work conducted in the Lao People’s Democratic Republic has previously demonstrated the diversity of this type of rice in terms of quality. The definition of a waxy rice variety is dependent on the meaning of amylose. The conventional method for determining amylose content has shown that waxy rice could have up to 5% amylose. However, including a 0% amylose standard in the standard curve causes the amylose content of these varieties to become 0-2%. In this work, the absence of amylose in waxy rice has been determined through three different approaches. Granule-bound starch synthase I (GBSS1), the enzyme which synthesises amylose, was not detected in waxy rice. Long linear chains associated with amylose were also not detected by size exclusion chromatography (SEC). The absence of these long chains affected functional properties of waxy rice, as indicated by the differences in viscosity curves between waxy and non-waxy rice. Moreover, these waxy varieties themselves exhibit differences in their viscosity curves, another indication of the diversity in coking properties in these varieties. A new approach, the ‘lnP(N) technique’, in analysing chain length distributions was applied to varieties with known mutations in two of the enzymes involved in the synthesis of amylopectin, and in determining gelatinisation temperature. It was determined that the presence of a novel feature, an interruption to linearity at DP 18-24, of the lnP(N) plot was found in rice samples with mutations in the alk gene, which codes for starch synthase (SS) IIa, and in samples with inactive branching enzyme (BE) IIb. Single nucleotide polymorphisms (SNPs) in the gene coding for SSIIa have been associated with lowered gelatinisation temperature. On the other hand, non-functionality of BEIIb changes the amylopectin structure such that gelatinisation temperature is increased. The novel feature of the lnP(N) plot is found when either or both SSIIa and BEIIb are non-functional. Waxy rice starch has hot-water-soluble (HWS) and insoluble (HWI) components. It has been confirmed that the soluble polysaccharides are structurally different from phytoglycogen, and are similar to amylopectin. Structural differences between the two fractions, which can account for their differences in solubility, were determined. At the level of the chain length distribution, the HWI fraction contained long chains not found in the HWS fraction. Considerable amounts of sucrose and glucose were found in the HWS fraction. At another level of structure, the degree of branching of the HWS components was higher than in the HWI fraction. On the other hand, the whole molecules of the HWS fraction were smaller than those of the HWI fraction. These structural differences between the two fractions potentially affected their physical behaviour, particularly solubility. The amount of leached material appears to be a property of the method, as varying cooking conditions changed the amount of HWS components. This amount reaches equilibrium at certain conditions, indicating the limited amount of the HWS material. On the other hand, the HWI component contains molecules that are insoluble in water, rather than molecules that solubilise slowly. Given the stability of the HWS fraction in solution, the ratio of the HWS fraction to the HWI fraction could potentially be used in measuring quality if the amount of the HWS fraction is variety-specific. However, the quantity of the HWS fraction appears to be a feature of the starch, rather than of the variety. Nevertheless, the fact that the soluble fraction is structurally and thermodynamically different from the insoluble fraction could presumably be grounds to classify the soluble component as a group of molecules distinct from amylopectin.
385

The analysis and stability of microencapsulated folic acid during the processing and preparation of instant Asian noodles.

Hau, Rodney, s3016872@student.rmit.edu.au January 2009 (has links)
Fortification of instant Asian noodles with folic acid has the potential to enhance dietary folate intakes. Recent studies show folate deficiency is prevalent in many countries. Furthermore, this vitamin is unstable upon exposure to light, air, heat and extreme conditions of acidity and alkalinity. Internationally, folate in foods has traditionally been analysed by a microbiological assay, however, due to the extensive time required for sample preparation and analysis, alternative procedures for analysis require consideration. The aims of the current study have been to investigate the stability of added folic acid in fortified instant fried noodles by analytical methods of capillary electrophoresis and reversed-phase HPLC. Additionally, procedures for the microencapsulation of folic acid by spray drying have been evaluated along with their significance in increasing the stability of the vitamin during processing and boiling of instant noodles. Optimisation of capillary electrophoretic conditions showed that the maximum response of folic acid relative to an internal standard was achieved using various concentrations of phosphate and borate. Analytical parameters including the effects of pH, voltage and temperature were studied along with enzymatic treatments for liberation of folic acid from the noodle matrix based. Higher recoveries were obtained using the enzymes however these exceeded 100% due to sample matrix interference. Standard addition or internal calibration were both effective in correcting for matrix interferences. Comparative investigations with reversed-phase HPLC confirmed the results obtained with the capillary electrophoresis. Using either a phosphate based buffer in conjunction with an ion-pairing agent at alkaline pH or an acidic mobile phase, the results attained were in good agreement as folic acid exhibited excellent stability under typical processing conditions. Various food approved hydrocolloids were evaluated for encapsulation of folic acid by spray drying. Incorporation of the microcapsules into formulations of instant fried noodles showed that after boiling the folic acid was chemically degraded to some extent and leaching also occurred. The microcapsules exhibited similar properties regardless of the binding agent used, with losses still occurring during the boiling stage. In order to enhance the structural integrity of the spray dried microcapsules, CaCl2 was used as a cross-linking agent for capsules prepared using alginate or pectin binding agents. Considerable increases in retention of core material were observed as the network exhibited a reduction in swelling and hydration, and subsequently a decrease in the release of folic acid. In summary, capillary electrophoresis and reversed-phase HPLC provided excellent separation and good quantitatation of added folic acid in instant Asian noodles. Excellent resolution was obtained between the sample matrix interference of instant noodles and the analysed vitamin. Folic acid displayed high stability throughout the processing of instant noodles whereas there was consistent evidence that unencapsulated folic acid was degraded during boiling. Microencapsulation of folic acid with combinations of alginate and pectin as the binding agents, proved to be effective in maintaining folic acid stability when calcium treatment was performed after spray drying. These findings provide an effective way to retain folic acid used in fortifying Asian instant noodles.
386

Validação de método analítico para quantificação de doripenem por eletroforese capilar e estudo da estabilidade por eletroforese capilar e ensaio microbiológico / Validation of analytical method for measurement of doripenem by capillary electrophoresis and study of stability by capillary electrophoresis and microbiological assay

Paliosa, Patrícia Klitzke January 2012 (has links)
O doripenem é um antibiótico carbapenêmico de amplo espectro e aprovado pelo Food and Drug administration (FDA) em 2007. Devido a sua recente comercialização, não está presente em códigos oficiais. Desta forma, esta dissertação teve como objetivo validar um método analítico para quantificação do Doripenem utilizando a eletroforese capilar (EC) como ferramenta analítica alternativa à Cromatografia Liquida de Alta Eficiência (CLAE), além de desenvolver métodos físico-químicos para caracterizar a matéria prima e estudar a cinética de degradação do fármaco frente à temperatura e radiação por luz UVC. Diante dos resultados obtidos, verificou-se que métodos de caracterização como a cromatografia em camada delgada, espectrofotometria de infravermelho e ultravioleta e espectroscopia de Ressonância Magnética Nuclear demonstraram ser satisfatórios para caracterização do fármaco, já os métodos como DSC e faixa de fusão não foram adequados. Para fins de comparação com a EC, realizou -se a covalidação do método de CLAE reportado na literatura, tendo sido obtido um fator de correlação de 0,9950, teor médio de I 00,09 % e recuperação de I OI , 19 %. Para o desenvolvimento do método por EC foi utilizado capilar de sílica fundida de 40 em efetivo com 50 11m de diâmetro interno, eletrólito tampão barato de sódio I 00 mM em pH 8,0, tensão aplicada de 15 kV a 25 ºC, comprimento de onda de 298 nm e, procainamida como padrão interno. O comprimento de onda 214 nm foi monitorado a presença de produtos de degradação. O método demonstrou ser específico, linear entre 25-250 11g/ml (r=0,9995) , preciso (I OI ,33 %), exato (I OI ,86 %) e robusto. Conforme os resultados obtidos, os métodos por CLAE e EC demonstraram ser intercambiáveis, contudo, a EC apresenta vantagens como menor tempo de análise e pequena quantidade de resíduo gerado. Para o estudo da cinética de degradação por EC e ensaio microbiológico (EM) , as condições verificadas foram temperatura (45 ºC, por 24 horas) e luz UVC (por 12 horas). O teor final de doripenem obtido pela EC foi de 70,74 e 64,18 % para temperatura e UVC, respectivamente. Já a potência verificada pelo ensaio microbiológico foi de 42,77 e 21 ,95 % para temperatura e UVC, respectivamente. / Doripenem is a carbapenemic antibiotic with a broad spectrum of action launched in 2005. Due to its recent commercialization, doripenem is not in official codes. So this dissertation aims to validate an analytical method to doripenem quantification using capillary electrophoresis (CE) as an alternative method to High Performance Liquid Chromatography (HPLC), besides to develop physic-chemical methods to characterize the material and to study the degradation kinetics of doripenem in UVC light and temperature (45 ºC). The characterization methods as thin layer chromatography, infrared and ultraviolet spectroscopy and spectroscopy Nuclear Magnetic Resonance proved to be satisfactory. Melting point range and DSC were not adequate to identify doripenem. To compare HPLC and EC, HPLC method was covalidate according literature. The method demonstrated a correlation factor 0.9950, average content 100.09 % and recovery 101.19 %. For the development of CE method was employed 40 em fused silica capillary in 50 11m inner, electrolyte 100 mM buffer sodium borate at pH 8.0, applied voltage 15 kV at 25 ºC, wavelength 298 nm, and procainamide as internai standard. The method demonstrated to be linear between 25-250 IJQ/ml (r=0.9995), precise (1 01.33 %), accurate (1 01.86 %) and robust. Based on these results, the HPLC and CE methods are interchangeable. However, EC presents advantages such as reduced analysis time and small residue generated. To kinetic degradation study by CE and microbiological assay (MS) conditions as temperature (45 ºC for 24 hours) and UVC light (12 hours) were tested. The final residual content for doripenem by EC was 70.74 % and 64.18 to UVC and temperature, respectively. The antimicrobial power checked by MS was 42.77 and 21 .95% for temperature and UVC, respectively.
387

Aplicação da técnica de eletroforese capilar para verificação e comparação da homogeneidade de dosagem em medicamentos industriais e magistrais

Aleixo, Fernanda Caroline January 2016 (has links)
Orientador: Prof. Dr. Alexandre Zatkovskis Carvalho / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2016. / No Brasil, onde a desigualdade social é evidente, nem todos os cidadãos têm acesso aos mesmos medicamentos. No entanto, algumas práticas como a distribuição de medicamentos pelo SUS, quebra de patentes, produção de genéricos e aviamento de medicamentos permitem que a população mais carente seja atendida em suas necessidades terapêuticas. Para que essas vantagens sejam efetivamente reais, deve-se garantir que a eficácia terapêutica dos medicamentos mais acessíveis seja similar à dos medicamentos de referência. Neste trabalho a técnica de eletroforese capilar foi utilizada para a comparação da qualidade de medicamentos. Desta forma, este trabalho constitui também um serviço público à população ao verificar comparativamente a qualidade de medicamentos de referência, genéricos, similares e magistrais utilizados para o tratamento de hipertensão, principalmente verificando a uniformidade de dosagem. A formulação escolhida para este estudo foi a associação de maleato de enalapril e hidroclorotiazida. Foram estudadas amostras do laboratório de referência, um genérico e um similar, na forma farmacêutica de comprimidos para administração via oral, além de duas formulações obtidas em farmácias magistrais, na forma farmacêutica de cápsulas. A identificação dos analitos foi realizada através da obtenção de espectros de absorção molecular. A exatidão do método de análise por eletroforese capilar de zona foi comprovada através de testes de recuperação realizados para todos os laboratórios analisados. A faixa aceita de teor de princípio ativo permitido pela farmacopeia brasileira é de 90 a 110% do valor declarado no rótulo do medicamento, condição satisfeita por todas as formulações testadas. Os testes de uniformidade de peso e dosagem das unidades de cada lote demonstraram que tanto os laboratórios industriais como os magistrais satisfazem os requerimentos da farmacopeia brasileira considerando 30 dias de tratamento, mesmo com grandes diferenças de preço ao consumidor. / Since social differences are remarkable in Brazil, not all citizens have access to the same drugs. However, some health-related policies such as drug distribution by SUS, early patent break, generic manufacture and compounding pharmacies allows less wealth population to access their health treatment. To make these advantages real the therapeutic efficacy of those inexpensive formulations must be assured, as are the reference drugs. In this work the capillary electrophoresis technique was used to compare the quality of medicines. This way, this work also offers a public service to the population due to its comparative study of the quality of anti-hypertensive reference medicine, generics, similar and formulations from compounding pharmacies, accessing principally dose uniformity. Oral pills of the association of enalapril maleate and hydrochlorothiazide were chosen for this study, including a reference drug (patent owner), one generic formulation and one similar formulation. Capsules from two compounding pharmacies were also analyzed. Brazilian Pharmacopoeia preconizes drug approved if active substance assay is between 90 to 110% of label. Weight and dosage uniformity tests of each batch showed that both industrial laboratories as compounding satisfy the requirements of Brazilian Pharmacopoeia given 30 days of treatment, even with large differences in price to the consumer.
388

ELETROFORESE CAPILAR: UM MÉTODO PARA DETERMINAÇÃO DE HIPOGLICEMIANTES COMO ADULTERANTES EM FORMULAÇÕES HERBÁREAS USADAS NO TRATAMENTO DO DIABETES / CAPILLARY ELECTROPHORESIS: A METHOD FOR THE DETERMINATION OF HYPOGLYCEMICS IN HERBAL FORMULATIONS USED FOR THE TREATMENT OF DIABETES

Ferreira, Marlise 24 August 2012 (has links)
The popularity of herbal medicines as adjuncts in the treatment of diabetes mellitus, has increased in recent years. However, recent studies have demonstrated the presence of synthetic drugs, as adulterants, in these formulations, what can cause serious problems to the health of the patient, since interactions and pharmacological effects are unpredictable. This work describes the development of a method for the simultaneous determination of metformin, glibenclamide, gliclazide and chlorpropamide employing capillary zone electrophoresis (CZE) with contactless conductivity detection (C4D). The work was carried out using a capillary electrophoresis system built in the laboratory. The optimized conditions for the determination of adulterants in herbal medicines by CZE-C4D were the following: 20 mmol L-1 sodium acetate at pH 10.0 as working electrolyte, separation potential of -15kV, separation temperature of 25ºC, indirect conductivity detection operating at 400 kHz and amplitude wave of 2 Vpp, hydrodynamic injection by gravity (20 cm left side elevation for 60 s). The method was validated and applied to the determination of hypoglycemics in pharmaceutical formulations commercialized by compounding pharmacies in Brazil. The method allows the identification of adulterants and its quantification from 0.24 mg to metformin, 0.15 mg to glibenclamide, 0.33 mg to gliclazide and 0.24 mg to chlorpropamide. / A popularidade dos fitoterápicos como coadjuvantes no tratamento do diabetes mellitus, tem aumentado nos últimos anos. No entanto, trabalhos recentes têm demonstrado a presença de fármacos sintéticos, como adulterantes, nestas formulações, o que pode causar sérios problemas à saúde do paciente, uma vez que interações e efeitos farmacológicos são imprevisíveis. Este trabalho descreve o desenvolvimento de um método para a determinação simultânea de metformina, glibenclamida, gliclazida e clorpropamida, empregando eletroforese capilar de zona (CZE) com detecção condutométrica sem contato (C4D), usando um sistema de eletroforese capilar construído em laboratório. As condições otimizadas para a determinação de adulterantes em fitoterápicos por CZE-C4D foram: eletrólito de trabalho acetato de sódio 20 mmol L-1 (pH 10,0); potencial de separação - 15 kV; temperatura de 25ºC; detecção indireta operando em 400kHz e amplitude de onda de 2vpp; e injeção por gravidade de 20 cm por 60 s. O método foi validado e aplicado para a avaliação de hipoglicemiantes em formulações herbáreas comercializadas por farmácias no mercado brasileiro. O método permite a identificação dos adulterantes e sua quantificação a partir de 0,24 mg para a metformina, 0,15 mg para a glibenclamida, 0,33 mg para a gliclazida e 0,24 mg para a clorpropamida.
389

Développements analytiques pour le criblage d'interactions lanthanides/ligands / Analytical developments for screening of lanthanides/ligands interactions

Varenne, Fanny 03 July 2012 (has links)
Ce travail étudie le potentiel de l'électrophorèse capillaire couplée à la spectrométrie de masse à ionisation par plasma (ICP/MS) pour le criblage d'une bibliothèque de ligands en fonction de leur affinité pour l'europium en milieu hydro-organique. Cette méthode permet, d'une part, d'évaluer l'affinité des ligands phosphorés en moins de deux heures et en utilisant moins de 15 ng de ligand, et d'autre part, de déterminer les constantes de complexation. Les résultats sont en accord avec ceux obtenus par titrage spectrophotométrique.Parallèlement, une bibliothèque de copolymères pour l'extraction solide/liquide de l'europium a été étudiée. Le protocole d'extraction mis au point permet de les classer selon leur affinité pour celui-ci en milieu hydro-organique et en utilisant 60 mg de copolymère. Pour les plus prometteurs, les propriétés de reconnaissance et la sélectivité La3+/Eu3+/Lu3+ ont été évaluées. / This work investigates the potential of hyphenated capillary electrophoresis and inductively coupled mass spectrometry to classify different ligands according to their europium binding affinity in a hydro-organic medium. On the one hand, this method enables to evaluate the affinity of phosphorus-containing ligands in less than two hours and using less than 15 ng of ligand. On the other hand, complexation constants could be determined. The results are in excellent agreement with the values obtained by spectrophotometric titrations.Moreover, a library of copolymers for solid/liquid extraction of europium is investigated. The extraction protocol enables to classify copolymers according to their europium affinity in a hydro-organic medium. This screening requires 60 mg of copolymers. For the most promising recognition properties and selectivity La3+/Eu3+/Lu3+ are evaluated.
390

"Validação e aplicação de novos métodos analíticos para análise de antidepressivos tricíclicos em amostras de plasma e formulações farmacêuticas" / Validation and aplication of new analitical methods for tricyclic antidepressants analysis in pharmaceutical formulations and plasma samples

Marcelo Delmar Cantú 05 March 2004 (has links)
A depressão, tida como a doença do final do século XX, acarreta diversos distúrbios físicos, mentais e emocionais. Amitriptilina,. imipramina, nortriptilina e desipramina são antidepressivos tricíclicos (ADT) largamente usados no tratamento de desordens depressivas. Os ADT são fármacos que apresentam alta variabilidade interindividual na farmacocinética e resposta clínica não facilmente ou não imediatamente mensurável. Assim faz-se necessário o desenvolvimento e validação de métodos analíticos capazes de determinar com a devida confiabilidade suas concentrações em amostras de plasma. Os métodos desenvolvidos possuem uma etapa de extração para posterior separação e quantificação. Os métodos de extração avaliados foram a extração líquido-líquido (LLE) e a microextração em fase sólida (SPME). As técnicas usadas para separação e quantificação foram cromatografia líquida (LC) e eletroforese capilar (CE). Dois métodos foram desenvolvidos e validados: LLE/LC e LLE/CE. Usando uma fibra com recobrimento PDMS 100 mm, um método SPME/LC (modo de dessorção off-line) foi desenvolvido e os parâmetros relativos a SPME foram otimizados fazendo uso de planejamento fatorial (23) e simplex. Usando as mesmas condições otimizadas para a fibra PDMS testou-se uma fibra PDMS/DVB 65 mm. Avaliou-se a CE para a determinação dos ADT em formulações farmacêuticas e o comportamento eletroforético destes compostos em diferentes meio (água, metanol e acetonitrila) foi avaliado. De acordo com os parâmetros avaliados (linearidade, precisão (intra e inter ensaios), recuperação, limites de quantificação (LOQ) e detecção) ambos os métodos (LLE/LC e LLE/CE) mostraram-se aplicáveis para a determinação dos ADT em níveis plasmáticos. O método SPME/LC (off-line) que fez uso da fibra com recobrimento PDMS/DVB apresentou LOQ suficientemente baixos para determinar os ADT em concentrações plasmáticas, apesar de consumir um tempo maior para execução, quando comparado aos métodos LLE/LE e LLE/CE. A validação e aplicação de um método fazendo uso de CE para a análise dos ADT em formulações farmacêuticas mostra a aplicabilidade desta técnica para análises de rotina. Determinou-se por CE o pKa* dos ADT em água, metanol e ACN. A ordem dos valores obtidos em meio aquoso e metanólico é inversa em relação a ordem obtida em ACN. Assim, pôde-se correlacionar a carga das espécies em cada condição de análise com a ordem de migração dos ADT em cada meio. / Depressive disorders imply in a variety of physical, mental and emotional disturbances. Amitriptyline, imipramine, nortriptyline e desipramine are tricyclic antidepressants (TAD) largely used in depression treatment. The TADs are drugs that show high inter individual variability in pharmacokinetics, low clinical response or even they are not straightforwardly measured. Therefore, it is necessary the development and validation of analytical methods for TAD determination in plasma samples. The developed methods have an extraction step for subsequently separation and quantification. The extraction methods appraised were liquid-liquid extraction (LLE) and solid phase microextraction (SPME). The analytical techniques used for separation and further quantification were liquid chromatography (LC) and capillary electrophoresis (CE). Two methods were developed and validated: LLE/LC and LLE/CE. Using a PDMS coating (100 mm), a SPME/LC method (with off-line dessorption) was developed and the experimental conditions relative to SPME were optimized using a factorial planning (23) and a simplex methodology. The same optimized conditions (for PDMS) were used for a PDMS/DVB (65 mm) coating. According to the appraised parameters such as linearity, precision (intra and inter assays), recovery and limits of quantification and detection, the methods LLE/LC and LLE/CE showed suitable for TAD determination in plasma samples regarding the therapeutic plasmatic concentration. The SPME/LC method (off-line desorption) with PDMS/DVB coating has also shown LOQ lower than the minimum therapeutic plasmatic concentration, implying that may be subject to validation. This method may be used for TAD analysis even though the total analysis time was greater those from LLE/LC and LLE/CE methods. CE was also applied for TAD determination in pharmaceutical formulations and the electrophoretic behavior such compounds in different separation media, especially non-aqueous solvents, was studied. The validation and application of a method using CE for TAD determination in pharmaceutical formulations has shown the applicability of this technique for routine analysis. The migration order in aqueous and methanolic media is opposite to obtained in acetonitrile, and the pKa* of the TAD were determined in different media (aqueous, methanol and acetonitrile) by CE. With the calculated values, it was possible to correlate the species total charge to the migration order in each medium.

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