988 resultados para CAPILLARY-ELECTROPHORESIS SYSTEM
Resumo:
Cholecystokinin (CCK) secretion in rats and humans is inhibited by pancreatic proteases and bile acids in the intestine. It has been hypothesized that the inhibition of CCK release caused by pancreatic proteases is due to proteolytic inactivation of a CCK-releasing peptide present in intestinal secretion. To purify the putative luminal CCK-releasing factor (LCRF), intestinal secretions were collected by perfusing a modified Thiry-Vella fistula of jejunum in conscious rats. From these secretions, the peptide was concentrated by ultrafiltration followed by low-pressure reverse-phase chromatography and purified by reverse-phase high-pressure liquid chromatography. Purity was confirmed by high-performance capillary electrophoresis. Fractions were assayed for CCK-releasing activity by their ability to stimulate pancreatic protein secretion when infused into the proximal small intestine of conscious rats. Partially purified fractions strongly stimulated both pancreatic secretion and CCK release while CCK receptor blockade abolished the pancreatic response. Amino acid analysis and mass spectral analysis showed that the purified peptide is composed of 70-75 amino acid residues and has a mass of 8136 Da. Microsequence analysis of LCRF yielded an amino acid sequence for 41 residues as follows: STFWAYQPDGDNDPTDYQKYEHTSSPSQLLAPGDYPCVIEV. When infused intraduodenally, the purified peptide stimulated pancreatic protein and fluid secretion in a dose-related manner in conscious rats and significantly elevated plasma CCK levels. Immunoaffinity chromatography using antisera raised to synthetic LCRF-(1-6) abolished the CCK releasing activity of intestinal secretions. These studies demonstrate, to our knowledge, the first chemical characterization of a luminally secreted enteric peptide functioning as an intraluminal regulator of intestinal hormone release.
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A lamotrigina (LTG) é um fármaco pertencente à classe das feniltriazinas utilizado no tratamento de crises epilépticas generalizadas e focais e no tratamento adjunto da epilepsia refratária. Devido à alta variabilidade interindividual, às interações medicamentosas e aos efeitos adversos apresentados durante a administração da LTG, a monitorização terapêutica nos pacientes que fazem uso deste fármaco é necessária para ajuste de dose individual e evitar os efeitos adversos. Assim, o objetivo deste trabalho foi a avaliação de duas técnicas de microextração: a microextração em fase líquida com fibras ocas (HF-LPME) e a microextração líquido-líquido dispersiva (DLLME) para análise da lamotrigina em amostras de plasma de pacientes epilépticos. Primeiramente foram definidas as condições eletroforéticas: foi utilizado um capilar de sílica fundida de 75 ?m de diâmetro interno e 50 cm de comprimento efetivo. O eletrólito de corrida (BGE) foi composto por ácido 2-morfolinoetanosulfônico (MES), na concentração de 130 mmol L-1 e pH 5,0. As análises foram realizadas à temperatura de 20°C e tensão de 15 kV. A amostra foi injetada hidrodinamicamente (0,5 psi por 10 s) e a detecção foi feita em 214 nm. Nestas condições a LTG e o padrão interno (PI), lidocaína, puderam ser analisados em menos de 7 minutos. A HF-LPME foi avaliada no modo de 3 fases, usando 500 ?L de plasma e 3,5 mL de solução fosfato de sódio 50 mmol L-1 pH 9,0 como fase doadora. O solvente utilizado para impregnar a fibra foi o 1-octanol. Como fase aceptora foram utilizados 60 ?L de solução de ácido clorídrico pH 4,0. Para avaliação da DLLME, foi necessária uma etapa de pré-tratamento da amostra (500 ?L de plasma) com 1 mL de acetonitrila. Após isto, 1,3 mL do sobrenadante foram adicionados a 4 mL de solução fosfato de sódio 50 mmol L-1 pH 9,0 e 120 ?L de clorofórmio (solvente extrator) foram injetados nesta amostra aquosa e 165 ?L de fase sedimentada foram recuperados. As características de desempenho analítico para ambos os métodos foram avaliadas, sendo obtida linearidade na faixa de concentração plasmática de 1-20 ?g/mL e limite inferior de quantificação (LIQ) de 1 ?g mL-1. Os ensaios de precisão e exatidão apresentaram valores de acordo com os guias oficiais. Além disso, os métodos foram seletivos, não apresentaram efeito residual e as amostras foram estáveis. Os valores de recuperação foram de 54,3 e 23% para HF-LPME e DLLME, respectivamente. Os métodos validados foram aplicados com sucesso em amostras de plasma de pacientes epilépticos em tratamento com a LTG. Além disso, as duas técnicas foram comparadas e a HF-LPME apresentou vantagens em relação à DLLME, mostrando ser uma técnica promissora para análise de matrizes complexas, com reduzido consumo de solvente orgânico e possibilidade de automação.
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Neste trabalho são apresentados processos de microfabricação de estruturas contendo microcanais e sistemas de manipulação hidrodinâmica e eletroosmótica de fluídos. Foram desenvolvidos processos de microfabricação utilizando toner sobre poliéster, toner sobre vidro, toner como resiste, além de métodos alternativos de perfuração de lâminas e selagem de microestruturas em vidro, desenvolvimento de microestruturas para eletroforese capilar e espectrometria de massas com ionização por eletronebulização. A caracterização dos materiais e processos permitiu uma ampla visão das potencialidades e alternativas dos processos de microfabricação, tendo sido demonstrado que os dispositivos produzidos em toner-poliéster são quimicamente resistentes às substâncias tipicamente utilizadas em eletroforese capilar. Neste trabalho, um detector condutométrico sem contato foi implementado em microestruturas de toner-poliéster e a separação eletroforética de alguns metais alcalinos é demonstrada. A microestrutura foi projetada no formato padrão em cruz, tendo o canal de separação 22 mm de comprimento, 12 µm de profundidade e largura típica. A cela condutométrica foi construída sobre o canal de separação utilizando-se fita adesiva de cobre (1 mm de largura) como eletrodos. O sinal aplicado na cela foi de 530 kHz e 10 Vpp . A separação de K+, Na+ e Li+ na concentração de 100 µmol L-1 foi efetuada em torno de 0,8 min, utilizando-se 1 kV como potencial de separação. Foram desenvolvidos microchips para análise por espectrometria de massas com introdução de amostra por eletronebulização, sendo determinado cluster do íon cloreto em concentração de 1 mmol L+. Também solução com 1 mmol/L de glucosamina em água/metanol 1: 1 (v/v), sob corrente de 100 nA gerou sinal estável e livre de descarga corona. Utilizando detecção amperométrica, obteve-se eletroferogramas mostrando a separação de iodeto (10 mmol L-1) e ascorbato (40 mmol L-1) em potencial de separação de 4,0 kV (800 V cm-1 potencial de detecção de 0,9 V (vs. Ag/AgCI), injeção com 1,0 kV/1°s, tampão borato de sódio 10 mmol L+ com CTAH 0,2 mmol L-1, pH 9,2. Obteve-se eficiência de 1,6.104 pratos/m e foi possível obter limites de detecção de 500 nmol L-1 (135 amol) e 1,8 µmol L-1 (486 amol) para iodeto e ascorbato, respectivamente. O processo de fabricação utilizando toner como material estrutural para microchips em vidro foi bem estabelecido, assim como os modos de detecção fotométrico e condutométrico foram demonstrados. Foram obtidos eletroferogramas par detecção condutométrica sem contato de solução 200 µmol L-1 de K+, Na+ e U+, em tampão histidina/ácido lático 30 mmol L-1 9:1 (v/v) água:metanol, injeção eletrocinética de 2,0 kV/5,0 s, potencial de separação de 1 kV, 530 kHz de frequência e tensão de 2,0 Vpp. Também foi implementado um sistema de detecção fotométrico para microchip operando em 660 nm, tendo sido utilizado para a detecção de azul de metileno 1,0 mmol L-1 em tampão de corrida de barato de sódio 20 mmol L-1 (pH 9,2), com o detector posicionado a 40 mm do ponto de injeção e com injeção eletrocinética a 2,0 kV por 12 s com picos bem resolvidos em menos de 1 min.
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Aims: Isolation, identification and characterization of a highly efficient isomaltulose producer. Methods and Results: After an enrichment procedure for bacteria likely to metabolize isomaltulose in sucrose-rich environments, 578 isolates were screened for efficient isomaltulose biosynthesis using an aniline/diphenylamine assay and capillary electrophoresis. An isolate designated UQ68J was exceptionally efficient in sucrose isomerase activity. Conversion of sucrose into isomaltulose by UQ68J (enzyme activity of 90-100 U mg(-1) DW) was much faster than the current industrial strain Protaminobacter rubrum CBS574.77 (41-66 U mg(-1) DW) or a reference strain of Erwinia rhapontici (0.3-0.9 U mg(-1) DW). Maximum yield of isomaltulose at 78-80% of supplied sucrose was achieved in less than half the reaction time needed by CBS574.77, and the amount of contaminating trehalulose (4%) was the lowest recorded from an isomaltulose-producing microbe. UQ68J is a Gram negative, facultatively anaerobic, motile, noncapsulate, straight rod-shaped bacterium producing acid but no gas from glucose. Based on 16S rDNA analysis UQ68J is closest to Klebsiella oxytoca, but it differs from Klebsiella in defining characteristics and most closely resembles Pantoea dispersa in phenotype. Significance and Impact of Study: This organism is likely to have substantial advantage over previously characterized sucrose isomerase producers for the industrial production of isomaltulose.
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Urinary proteomics is emerging as a powerful non-invasive tool for diagnosis and monitoring of variety of human diseases. We tested whether signatures of urinary polypeptides can contribute to the existing biomarkers for coronary artery disease (CAD). We examined a total of 359 urine samples from 88 patients with severe CAD and 282 controls. Spot urine was analyzed using capillary electrophoresis on-line coupled to ESI-TOF-MS enabling characterization of more than 1000 polypeptides per sample. In a first step a "training set" for biomarker definition was created. Multiple biomarker patterns clearly distinguished healthy controls from CAD patients, and we extracted 15 peptides that define a characteristic CAD signature panel. In a second step, the ability of the CAD-specific panel to predict the presence of CAD was evaluated in a blinded study using a "test set." The signature panel showed sensitivity of 98% (95% confidence interval, 88.7-99.6) and 83% specificity (95% confidence interval, 51.6-97.4). Furthermore the peptide pattern significantly changed toward the healthy signature correlating with the level of physical activity after therapeutic intervention. Our results show that urinary proteomics can identify CAD patients with high confidence and might also play a role in monitoring the effects of therapeutic interventions. The workflow is amenable to clinical routine testing suggesting that non-invasive proteomics analysis can become a valuable addition to other biomarkers used in cardiovascular risk assessment.
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Purine and pyrimidine triplex-forming oligonucleotides (TFOs), as potential antibacterial agents, were designed to bind by Hoogsteen and reverse Hoogsteen hydrogen bonds in a sequence specific manner in the major groove of genomic DNA at specific polypurine sites within the gyrA gene of E. coli and S. pneumoniae. Sequences were prepared by automated synthesis, with purification and characterisation determined by high performance liquid chromatograpy, capillary electrophoresis and mass spectrometry. Triplex stability was assessed using melting curves where the binding of the third strand to the duplex target, was assessed over a temperature range of 0-80°C, and at pH 6.4 and 7.2. The most successful of the unmodified TFOs (6) showed a Tm value of 26 °C at both pH values with binding via reverse Hoogsteen bonds. Binding to genomic DNA was also demonstrated by spectrofluorimetry, using fluorescein-labelled TFOs, from which dissociation constants were determined. Modifications in the form of 5mC, 5' acridine attachment, phosphorothioation, 2'-0-methylation and phosphoramidation, were made in order to. increase Tm values. Phosphoramidate modification was the most with increased Tm values of 42°C. However, the final purity of these sequences was poor due to their difficult syntheses. FACS (fluorescent activated cell sorting) analysis was used to determine the potential uptake of a fluorescently labelled analogue of 6 via passive, coJd shock mediated, and anionic liposome aided, uptake. This was established at 20°C and 37°C. At both temperatures anionic lipid-mediated uptake produced unrivalled fluorescence, equivalent to 20 and 43% at 20 and 37°C respectively. Antibacterial activity of each oligonucleotide was assessed by viable count anaJysis relying on passive uptake, cold shocking techniques, chlorpromazine-mediated uptake, and, cationic and anionic lipid-aided uptake. All oligonucleotides were assessed for their ability to enhance uptake, which is a major barrier to the effectiveness of these agents. Compound 6 under cold shocking conditions produced the greatest consistent decline in colony forming units per ml. Results for this compound were sometimes variable indicating inconsistent uptake by this particular assay method.
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Accurate knowledge of the time since death, or postmortem interval (PMI), has enormous legal, criminological, and psychological impact. In this study, an investigation was made to determine whether the relationship between the degradation of the human cardiac structure protein Cardiac Troponin T and PMI could be used as an indicator of time since death, thus providing a rapid, high resolution, sensitive, and automated methodology for the determination of PMI. ^ The use of Cardiac Troponin T (cTnT), a protein found in heart tissue, as a selective marker for cardiac muscle damage has shown great promise in the determination of PMI. An optimized conventional immunoassay method was developed to quantify intact and fragmented cTnT. A small sample of cardiac tissue, which is less affected than other tissues by external factors, was taken, homogenized, extracted with magnetic microparticles, separated by SDS-PAGE, and visualized with Western blot by probing with monoclonal antibody against cTnT. This step was followed by labeling and available scanners. This conventional immunoassay provides a proper detection and quantitation of cTnT protein in cardiac tissue as a complex matrix; however, this method does not provide the analyst with immediate results. Therefore, a competitive separation method using capillary electrophoresis with laser-induced fluorescence (CE-LIF) was developed to study the interaction between human cTnT protein and monoclonal anti-TroponinT antibody. ^ Analysis of the results revealed a linear relationship between the percent of degraded cTnT and the log of the PMI, indicating that intact cTnT could be detected in human heart tissue up to 10 days postmortem at room temperature and beyond two weeks at 4C. The data presented demonstrates that this technique can provide an extended time range during which PMI can be more accurately estimated as compared to currently used methods. The data demonstrates that this technique represents a major advance in time of death determination through a fast and reliable, semi-quantitative measurement of a biochemical marker from an organ protected from outside factors. ^
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The thesis primarily reports the synthesis, characterization and application of novel mixed mode stationary phases for Hydrophilic Interaction Liquid Chromatography (HILIC). HILIC is a rapidly emerging chromatographic mode that is finding great applicability in the analysis of polar organic molecules. In addition, there is a chapter on the analysis of Bisphenol A and related species using capillary electrophoresis (CE) coupled with boron-doped diamond electrodes for electrochemical detection. The synthesis and characterization of the novel mixed mode stationary phases prepared in this work is an important contribution to the field as the materials prepared exhibited better performance than similar materials obtained commercially. In addition a more thorough characterization of the materials (e.g.,thermogravimetric analysis, various NMR modes, elemental analysis, etc.) and resulting columns (e.g., H) than is typically encountered. The application of these new materials to the analysis of sugars using evaporative light scattering is also novel. In CE studies, electrochemical detection is sufficiently rare that the work is also novel.
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The chemical characterization of filter high volume (HV) and Berner impactor (BI) samples PM during RHaMBLe (Reactive Halogens in the Marine Boundary Layer) 2007 shows that the Cape Verde aerosol particles are mainly composed of sea salt, mineral dust and associated water. Minor components are nss-salts, OC and EC. The influence from the African continent on the aerosol constitution was generally small but air masses which came from south-western Europe crossing the Canary Islands transported dust to the sampling site together with other loadings. The mean mass concentration was determined for PM10 to 17 µg/m**3 from impactor samples and to 24.2 µg/m**3 from HV filter samples. Non sea salt (nss) components of PM were found in the submicron fractions and nitrate in the coarse mode fraction. Bromide was found in all samples with much depleted concentrations in the range 1-8 ng/m**3 compared to fresh sea salt aerosol indicating intense atmospheric halogen chemistry. Loss of bromide by ozone reaction during long sampling time is supposed and resulted totally in 82±12% in coarse mode impactor samples and in filter samples in 88±6% bromide deficits. A chloride deficit was determined to 8% and 1% for the coarse mode particles (3.5-10 µm; 1.2-3.5 µm) and to 21% for filter samples. During 14 May with high mineral dust loads also the maximum of OC (1.71 µg/m**3) and EC (1.25 µg/m**3) was measured. The minimum of TC (0.25 µg/m**3) was detected during the period 25 to 27 May when pure marine air masses arrived. The concentrations of carbonaceous material decrease with increasing particle size from 60% for the ultra fine particles to 2.5% in coarse mode PM. Total iron (dust vs. non-dust: 0.53 vs. 0.06 µg/m**3), calcium (0.22 vs. 0.03 µg/m**3) and potassium (0.33 vs. 0.02 µg/m**3) were found as good indicators for dust periods because of their heavily increased concentration in the 1.2 to 3.5 µm fraction as compared to their concentration during the non-dust periods. For the organic constituents, oxalate (78-151 ng/m**3) and methanesulfonic acid (MSA, 25-100 ng/m**3) are the major compounds identified. A good correlation between nss-sulphate and MSA was found for the majority of days indicating active DMS chemistry and low anthropogenic influences.
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Background: There is an urgent need to identify molecular signatures in small cell lung cancer (SCLC) that may select patients who are likely to respond to molecularly targeted therapies. In this study, we investigate the feasibility of undertaking focused molecular analyses on routine diagnostic biopsies in patients with SCLC.
Methods: A series of histopathologically confirmed formalin-fixed, paraffin-embedded SCLC specimens were analysed for epidermal growth factor receptors (EGFR), KRAS, NRAS and BRAF mutations, ALK gene rearrangements and MET amplification. EGFR and KRAS mutation testing was evaluated using real time polymerase chain reaction (RT-PCR cobas®), BRAF and NRAS mutations using multiplex PCR and capillary electrophoresis-single strand conformation analysis, and ALK and MET aberrations with fluorescent in situ hybridization. All genetic aberrations detected were validated independently.
Results: A total of 105 patients diagnosed with SCLC between July 1990 and September 2006 were included. 60 (57 %) patients had suitable tumour tissue for molecular testing. 25 patients were successfully evaluated for all six pre-defined molecular aberrations. Eleven patients failed all molecular analysis. No mutations in EGFR, KRAS and NRAS were detected, and no ALK gene rearrangements or MET gene amplifications were identified. A V600E substitution in BRAF was detected in a Caucasian male smoker diagnosed with SCLC with squamoid and glandular features.
Conclusion: The paucity of patients with sufficient tumour tissue, quality of DNA extracted and low frequency of aberrations detected indicate that alternative molecular characterisation approaches are necessary, such as the use of circulating plasma DNA in patients with SCLC.
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The alginic acid or alginates are acidic polysaccharides found in brown seaweed widely used in food, cosmetic, medical and pharmaceutical industry. This paper proposes the extraction, chemical characterization and verification of the pharmacological activities of brown seaweed variegata Lobophora . The alginate was extracted from the seaweed Lobophora variegata and part was sulphated for comparative purposes. The native extract showed 42% total sugar, 65% uronic acid, 0,36 % protein and 0% of sulfate, while the sulfate showed 39% , 60%, 0.36% and 27,92 % respectively. The presence of a sulfate group may be observed by the metachromasia with toluidine blue in electrophoresis system and characteristic vibration 1262,34 cm-1 in infrared spectroscopy connections assigned to S = O. We observed the formation of films and beads of native alginate, where more concentrated solution 6% resulted in a thicker and more consistent film. Native alginate showed proliferative activity at concentrations (25 and 50 mcg), (50 mg) and (100 mg) in 3T3 cell line in 24h, 48h and 72h, respectively , as the sulfated (100 mg) in 24 . Also showed antiproliferative or cytotoxic activity in HeLa cells of strain, (25 and 100 mg), (25 and 100 mg) and (25, 50 and 100 mg), to native, now for the sulfate concentrations (100 mg) in 24 (25, 50 and 100 mg) in 48 hours, and (50 and 100 mg ) 72h. For their antioxidant activity, the sulfated alginates have better total antioxidant activity reaching 29 % of the native activity while 7.5 % of activity . For the hydroxyl radical AS showed high inhibition ( between 77-83 % ) in concentrations, but the AN surpassed these numbers in the order of 78-92 % inhibition. The reducing power of AN and AS ranged between 39-82 % . In the method of ferric chelation NA reached 100 % chelating while the AS remained at a plateau oscillating 6.5%. However, in this study , we found alginates with promising pharmacological activities, to use in various industries as an antioxidant / anti-tumor compound
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A self-flotator vibrational prototype electromechanical drive for treatment of oil and water emulsion or like emulsion is presented and evaluated. Oil production and refining to obtain derivatives is carried out under arrangements technically referred to as on-shore and off-shore, ie, on the continent and in the sea. In Brazil 80 % of the petroleum production is taken at sea and area of deployment and it cost scale are worrisome. It is associated, oily water production on a large scale, carrier 95% of the potential pollutant of activity whose final destination is the environment medium, terrestrial or maritime. Although diversified set of techniques and water treatment systems are in use or research, we propose an innovative system that operates in a sustainable way without chemical additives, for the good of the ecosystem. Labyrinth adsor-bent is used in metal spirals, and laboratory scale flow. Equipment and process patents are claimed. Treatments were performed at different flow rates and bands often monitored with control systems, some built, other bought for this purpose. Measurements of the levels of oil and grease (OGC) of efluents treaty remained within the range of legal framework under test conditions. Adsorbents were weighed before and after treatment for obtaining oil impregna-tion, the performance goal of vibratory action and treatment as a whole. Treatment technolo-gies in course are referenced, to compare performance, qualitatively and quantitatively. The vibration energy consumption is faced with and without conventional flotation and self-flotation. There are good prospects for the proposed, especially in reducing the residence time, by capillary action system. The impregnation dimensionless parameter was created and confronted with consecrated dimensionless parameters, on the vibrational version, such as Weber number and Froude number in quadratic form, referred to as vibrational criticality. Re-sults suggest limits to the vibration intensity
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The use of capillary electrophoresis (CE) has been restricted to applications having high sample concentrations because of its low sensitivity caused by small injection volumes and, when ultraviolet (UV) detection is used, the short optical path length. Sensitivity in CE can be improved by using more sensitive detection systems, or by preconcentration techniques which are based on chromatographic and/or electrophoretic principles. One of the promising strategies to improve sensitivity is solid phase extraction (SPE). Solid Phase Extraction utilizes high sample volumes and a variety of complex matrixes to facilitate trace detection. To increase the specificity of the SPE a selective solid phase must be chosen. Immunosorbents, which are a combination of an antibody and a solid support, have proven to be an excellent option because of high selectivity of the antibody. This thesis is an exploratory study of the application of immunosorbent-SPE combined with CE for trace concentration of benzodiazepines. This research describes the immobilization and performance evaluation of an immunosorbent prepared by immobilizing a benzodiazepine-specific antibody on aminopropyl silica. The binding capacity of the immunosorbent, measured as µg of benzodiazepine/ gram of immunosorbent, was 39 ± 10. The long term stability of the prepared immunosorbent has been improved by capping the remaining aminopropyl groups by reaction with acetic anhydride. The capped immunosorbent retained its binding capacity after several uses.
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The aim of this study was to develop and validate selective and sensitive methods for quantitative determination of an antibacterial agent, gemifloxacin, in tablets by high performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE). The HPLC method was carried out on a LiChrospher (R) 100 RP-8e, 5 mu m (125 x 4 mm) column with a mobile phase composed of tetrahydrofuran-water (25:75, v/v) with 0.5 % of triethylamine and pH adjusted to 3.0 with orthophosphoric acid. The CZE method was performed using 50 mM sodium tetraborate buffer (pH 8.6). Samples were injected hydrodynamicaly (0.5 psi, 5 s) and the electrophoretic system was operated under normal polarity, at +20 kV and capillary temperature of 18 degrees C. A fused-silica capillary 40.2 cm (30 cm effective length) x 75 mu m i.d. was used. Both, HPLC and CZE could be interesting and efficient techniques to be applied for quality control in pharmaceutical industries.