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Dive into the research topics where Neila M. Cassiano is active.

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Featured researches published by Neila M. Cassiano.


Journal of Chromatography B | 2002

Enantiomeric determination of pantoprazole in human plasma by multidimensional high-performance liquid chromatography

Quezia B. Cass; Ana Luiza G. Degani; Neila M. Cassiano; J. Pedrazolli

Multidimensional HPLC is a powerful tool for the analysis of samples of a high degree of complexity. This work reports the use of multidimensional HPLC by coupling a RAM column with a chiral polysaccharide column to the analysis of Pantoprazole in human plasma by direct injection. The enantiomers from the plasma samples were separated with high resolution on a tris(3,5-dimethoxyphenylcarbamate) of amylose phase after clean-up by a RAM BSA octyl column. Water was used as solvent for the first 5 min in a flow-rate of 1.0 ml/min for the elution of the plasmatic proteins and then acetonitrile-water (35:65 v/v) for the transfer and analysis of pantoprazole enantiomers, which were detected by UV at 285 nm. Analysis time was 28 min with no time spent on sample preparation. A good linear relationship was obtained in the concentration range of 0.20 to 1.5 microg/ml for each enantiomer. Inter and intra-day precision and accuracy were determined by one low (0.24 microg/ml), one medium (0.70 microg/ml) and one high (1.3 microg/ml) plasma concentration and gave a C.V. varying from 1.80 to 8.43% and accuracy from 86 to 92%. Recoveries of pantoprazole enantiomers were in the range of 93.7-101.2%. The validated method was applied to the analysis of the plasma samples obtained from ten Brazilian volunteers who received an 80 mg oral dose of racemic pantoprazole and was able to quantify the enantiomers of pantoprazole in all clinical samples analyzed.


Bioanalysis | 2009

Restricted-access media supports for direct high-throughput analysis of biological fluid samples: review of recent applications

Neila M. Cassiano; Juliana Cristina Barreiro; Marcela Cristina de Moraes; Regina V. Oliveira; Quezia B. Cass

This review presents an update on the use of restricted-access materials (RAMs) for direct injection of biological samples. The fundamental improvements in the preparation of tailored RAMs and the diversity of applications with these phases are presented. Insights into diminishing the matrix effect by the use of RAM supports in methods by LC-MS and into the low number of methods for enantiomeric separations by direct injections of biological samples are addressed. The diversity of systems that incorporate RAMs for selective sample clean-up or fractionation in proteome and peptidome analysis is also covered.


Química Nova | 2009

Validação em métodos cromatográficos para análises de pequenas moléculas em matrizes biológicas

Neila M. Cassiano; Juliana Cristina Barreiro; Lúcia Regina Rocha Martins; Regina V. Oliveira; Quezia B. Cass

Chromatographic methods are commonly used for analysis of small molecules in different biological matrices. An important step to be considered upon a bioanalytical methods development is the capacity to yield reliable and reproducible results. This review discusses validation procedures adopted by different governmental agencies, such as Food and Drug Administration (USA), European Union (EU) and Agencia Nacional de Vigilância Sanitaria (BR) for quantification of small molecules by bioanalytical chromatographic methods. The main parameters addressed in this review are: selectivity, linearity, precision, accuracy, quantification and detection limits, recovery, dilution integrity, stability and robustness. Also, the acceptance criterions are clearly specified.


Chirality | 2010

Two-dimensional chromatography method applied to the enantiomeric determination of lansoprazole in human plasma by direct sample injection.

Ricardo F. Gomes; Neila M. Cassiano; J. Pedrazzoli; Quezia B. Cass

A two-dimensional HPLC method based on the direct injection of biological samples has been developed and validated for the determination of lansoprazole enantiomers in human plasma. The lansoprazole enantiomers were extracted from the biological matrix using an octyl restricted access media bovine serum albumin column (C8 RAM BSA) and the enantioseparation was performed on an amylose tris(3,5-dimethoxyphenylcarbamate) chiral column using acetonitrile:water (35:65 v/v) and UV detection at 285 nm. Analysis time was 25 min with no time spent on sample preparation. The method was applied to the analysis of the plasma samples obtained from nine Brazilian volunteers who received a 30 mg oral dose of racemic lansoprazole and was able to quantify the enantiomers of lansoprazole in the clinical samples analyzed.


Journal of Liquid Chromatography & Related Technologies | 2003

Effects on Enantioselectivity by the Use of Polysaccharide‐Based Columns by Multimodal Elution

Quezia B. Cass; Ana Luiza G. Degani; Neila M. Cassiano

Abstract The effects in chiral recognition of polysaccharide‐based stationary phases by changing the chromatographic mode and elution conditions were investigated for a series of three congeneric chiral sulfoxides: omeprazole, lanzoprazole and pantoprazole and the hydroxyl compound metyrapol. They were chromatographically analyzed at normal, polar, organic, and reversed‐phase elution modes, under the same conditions, with columns of cellulose and amylose tris(3,5‐dimethylphenylcarbamate), amylose tris(3,5‐dimethoxy‐phenylcarbamate), and amylose tris[(S)‐1‐phenylethylcarbamate] phases. This systematic, comparative study of the four chiral phases using a single column on the three different chromatographic modes, has highlighted that changing the chromatographic mode and/or composition of the mobile phase can dramatically affect the enantioselectivity and/or enantioresolution of the polysaccharide‐based columns. These differences were due solely to mobile phase effect and not to column batch effect. The quality of the performance of the four columns was maintained during the complete study. Excellent enantioresolutions were obtained for the four chiral compounds in two out of the four chiral phases in at least two of the three chromatographic modes.


Journal of Liquid Chromatography & Related Technologies | 2000

THE USE OF A POLYSACCHARIDE-BASED COLUMN ON MULTIMODAL ELUTION

Quezia B. Cass; Ana Luiza G. Degani; Neila M. Cassiano

Amylose tris (3,5-dimethylphenylcarbamate) coated onto APS-Hypersil (5 μm particle size and 120 Å pore size) was used under normal, reversed-phase and polar-organic conditions for the enantioseparation of six racemates of different classes. The CSP was not altered when going from one mobile phase to another. All compounds were enantioresolved within the elution modes with excellent selectivity factor. The simultaneous analysis of metyrapol enantiomers and metyrapone on reversed-phase conditions and the separation of the enantiomers of omeprazole in human plasma in the polar-organic mode of elution are also described.


Bioanalysis | 2012

Direct bioanalytical sample injection with 2D LC–MS

Neila M. Cassiano; Juliana Cristina Barreiro; Regina V. Oliveira; Quezia B. Cass

New analytical platforms have been developed in response to the need for attaining increased peak capacity for multicomponent complex analysis with higher sensitivity and characterization of the analytes, and high-throughput capabilities. This review outlines the fundamental principles of target and comprehensive 2D LC method development and encompasses applications of LC-LC and LC × LC coupled to MS in bioanalysis using a variety of online analytical procedures. It also provides a rationale for the usage of the most employed mass analyzers and ionization sources on these platforms.


Química Nova | 2010

Fases estacionárias quirais para cromatografia líquida de alta eficiência

Tiago C. Lourenço; Neila M. Cassiano; Quezia B. Cass

The development of Chiral Stationary Phases (CSPs) for high performance liquid chromatography has been studied by various researches around the world, especially, since 1980. This simple interest has been transformed into a tool of great technological value for the industrial community and scholars in general providing the existence of several CSPs, which act through different mechanisms of chiral discrimination. This paper describes the main types of CSPs that are used for the resolution of the majority of chiral compounds.


Journal of the Brazilian Chemical Society | 2013

New Trends in sample preparation in Brazil: an overview of bioanalytical applications by liquid chromatography

Neila M. Cassiano; Juliana Cristina Barreiro; Quezia B. Cass

This paper reviews the new technologies used for bioanalytical sample preparation as developed and explored by Brazilian researchers. Off-line, at-line and on-line sample clean-up approaches, as well microextraction systems, have been critically discussed. The main gains in these applications are enhanced sensitivity with cleaner samples and/or high-throughput capabilities.


Química Nova | 1998

Potencialidades do dióxido de chumbo eletrodepositado como sensor potenciométrico

Milton Duffles Capelato; Neila M. Cassiano

This paper proposes an experiment to be performed in both instrumental analysis and experimental physical-chemistry curricular disciplines in order to open options to develop challenging basic research activities. Thus the experimental procedures and the results obtained in the preparation of electrodeposited lead dioxide onto graphite and its evaluation as potentiometric sensor for H3O+ and Pb2+ ions, are presented. The data obtained in acid-base titrations were compared with those of the traditional combination glass electrode at the same conditions. Although a linear sub-Nernstian response to free hydrogen ions was observed for the electrodeposited PbO2 electrode, a good agreement was obtained between them. Working as lead(II) sensing electrode, the PbO2 showed a linear sub-Nernstian behavior at total Pb2+ concentrations ranging from 3,5 x 10-4 to 3,0 x 10-2 mol/L in nitrate media. For the redox couple PbO2/Pb(II) the operational slope converges to the theoretical one, as the acidity of the working solution increases.

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Quezia B. Cass

Federal University of São Carlos

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Regina V. Oliveira

Federal University of São Carlos

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Ana Luiza G. Degani

Federal University of São Carlos

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Juliana Cristina Barreiro

Federal University of São Carlos

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Lúcia Regina Rocha Martins

Federal University of São Carlos

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Milton Duffles Capelato

Federal University of São Carlos

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Tiago C. Lourenço

Federal University of São Carlos

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Bianca Rebelo Lopes

Federal University of São Carlos

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Bruno D. Rondon

Federal University of São Carlos

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