State-of-the-art and recent developments of immobilized polysaccharide-based chiral stationary phases for enantioseparations by high-performance liquid chromatography (2013–2017)

Polysaccharide-based chiral stationary phases have been recognized as one of the most powerful ones for high performance liquid chromatography (HPLC) separations of chiral compounds in analytical and also in preparative scale. Immobilized polysaccharide-based chiral stationary phases constitute a remarkable achievement due to their stable nature on working with standard or common solvents and also with those prohibited for using with coated phases. This review is mainly focused on the i. applications of these chiral stationary phases in numerous fields of HPLC separations; ii. comparative aspects between immobilized vs. coated polysaccharide-derived phases, and iii. revision of several theoretical studies such as enantiorecognition mechanism, mobile phase composition and column temperature effects.Fil: Padró, Juan Manuel. Universidad Nacional de La Plata, Facultad de Ciencias Exactas, Laboratorio de Investigación y Desarrollo de Métodos Analíticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Keunchkarian, Sonia. Universidad Nacional de La Plata, Facultad de Ciencias Exactas, Laboratorio de Investigación y Desarrollo de Métodos Analíticos; Argentin

State-of-the-art and recent developments of immobilized polysaccharide-based chiral stationary phases for enantioseparations by high-performance liquid chromatography (2013–2017)

Polysaccharide-based chiral stationary phases have been recognized as one of the most powerful ones for high performance liquid chromatography (HPLC) separations of chiral compounds in analytical and also in preparative scale. Immobilized polysaccharide-based chiral stationary phases constitute a remarkable achievement due to their stable nature on working with standard or common solvents and also with those prohibited for using with coated phases. This review is mainly focused on the i. applications of these chiral stationary phases in numerous fields of HPLC separations; ii. comparative aspects between immobilized vs. coated polysaccharide-derived phases, and iii. revision of several theoretical studies such as enantiorecognition mechanism, mobile phase composition and column temperature effects.Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA

Estudio cromatográfico de asociación entre solutos y selectores quirales en fase móvil : Aplicación al desarrollo de nuevas fases estacionarias quirales

Las metas específicas de este trabajo son las que siguen: 1. Evaluación de la capacidad de discriminación de aditivos quirales provenientes de alcaloides naturales de la familia de las cinconas, específicamente de quinina y de cinconidina. Algunos derivados de alcaloides de cincona, principalmente carbamatos, ya han sido estudiados en su potencialidad como selectores quirales en fase móvil normal y en fase estacionaria por Wolfgang Lindner en la Universidad de Viena. Dichas fases fueron el antecedente que ha inspirado el presente trabajo de tesis. 2. Estudio del(los) mecanismo(s) involucrado(s) en el reconocimiento quiral de aminoácidos. 3. Desarrollo de fases estacionarias de tipo "Pirkle" por modificación de la superficie del soporte con el(los) selector(es) unidos covalentemente. Evaluación de la influencia de la fijación sobre la capacidad enantioselectiva del material resultante. 4. Estudio crítico de la influencia de distintas condiciones cromatográficas (solventes, pH, temperatura, fuerza iónica) sobre la retención y la enantioseparación. Optimización de la enantioresolución de a-aminoácidos.Facultad de Ciencias Exacta

Predicting retention in reverse-phase liquid chromatography at different mobile phase compositions and temperatures by using the solvation parameter model

The prediction capability of the solvation parameter model in reverse-phase liquid chromatography at different methanol-water mobile phase compositions and temperatures was investigated. By using a carefully selected set of solutes, the training set, linear relationships were established through regression equations between the logarithm of the solute retention factor, logk, and different solute parameters. The coefficients obtained in the regressions were used to create a general retention model able to predict retention in an octadecylsilica stationary phase at any temperature and methanol-water composition. The validity of the model was evaluated by using a different set (the test set) of 30 solutes of very diverse chemical nature. Predictions of logk values were obtained at two different combinations of temperature and mobile phase composition by using two different procedures: (i) by calculating the coefficients through a mathematical linear relationship in which the mobile phase composition and temperature are involved; (ii) by using a general equation, obtained by considering the previous results, in which only the experimental values of temperature and mobile phase composition are required. Predicted logk values were critically compared with the experimental values. Excellent results were obtained considering the diversity of the test set.Fil: Gotta, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Keunchkarian, Sonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Reta, Mario Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentin

Enantiomeric separations by capillary electrophoresis: Theoretical method to determine optimum chiral selector concentration

A method to optimize the ligand concentration [S] in the background electrolyte of capillary electrophoresis separations is presented. It is based on the use of a model which predicts apparent electrophoretic mobilities as a function of ligand concentration (expressed as p[S] = −log[S]). This model is employed to compose the expression of a recently proposed criterion to qualify separations in electrophoresis. Two strategies to find the optimum p[S], leading to the best separation of all compounds, are explained: 1.- a graphical method using a windows map depicting the single separation criteria between all possible combination of compounds by pairs, and 2.- an analytical method where an extended multicriterion optimization function is composed and optimum p[S] is found by mathematical maximization. The procedure is applied to a hard-to-separate model system: enantiomeric separations of racemic mixtures. 2-Hydroxypropyl-β-cyclodextrin was chosen as a model ligand, and four pharmaceutical drugs as model analytes. In order to demonstrate the performance of the procedure, results of electrophoretic separations obtained at p[S] found as optimum are compared with separations obtained at p[S] values slightly higher and lower than the optimum.Fil: Lancioni, Carlina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Keunchkarian, Sonia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gagliardi, Leonardo Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Determination of thermodynamic binding constants by affinity capillary electrophoresis

A strategy to study thermodynamic binding constants by affinity capillary electrophoresis (ACE) is presented. In order to simplify mathematical treatment, analogy with acid-base dissociation equilibrium is proposed: instead of ligand concentration [X], negative logarithm of ligand concentration (or activity), pX = -log[X], is used. On this base, and taking into account ionic activities, a general procedure for obtaining thermodynamic binding constants is proposed. In addition, the method provides electrophoretic mobilities of the free analyte and analyte-ligand complex, even when binding constants are low and thus, the complexed analyte fraction is also low. This is useful as a base to rationally analyze a diversity of situations, i.e., different mathematical dependencies are obtained when analytes and ligands with different charges are combined. Practical considerations are given for carrying out a full experimental design. Enantiomeric ACE separation based on the use of chiral selectors is addressed. 2-hydroxypropyl-β-cyclodextrin was chosen as a model ligand, and both enantiomeric forms of four pharmaceutical drugs (propranolol, pindolol, oxprenolol and homatropine methylbromide) were considered as model analytes. Practical aspects are detailed and thermodynamic binding constants as well as free and complexed analytes mobilities are determined.Fil: Lancioni, Carlina. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Grupo Cromatografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Keunchkarian, Sonia. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Grupo Cromatografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Castells, Cecilia Beatriz Marta. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Gagliardi, Leonardo Gabriel. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Determination of amino acid content and its enantiomeric composition in honey samples from Mendoza, Argentina

The amino acid (AA) content in honeys from Mendoza (Argentina) was determined by high-performance liquid chromatography and the relative quantities of D- and L-AAs were determined by chiral gas chromatography coupled to mass spectrometry. The results showed that proline was the most abundant AA in all analyzed samples, followed by phenylalanine. Based on the AA content, different chemometric tools were assessed for provenance differentiation. The unsupervised chemometric methods, however, could not differentiate unquestionably the geographical origin of honey based only on their AA content. Enantiomeric ratio demonstrated that D-proline amount was lower than D-phenylalanine levels in practically all honey samples. In addition, D-enantiomers of alanine, valine, glutamic acid, leucine, and isoleucine were found in most samples. The study demonstrated that certain D-AAs can occur naturally in this foodstuff, probably, as a consequence of the Maillard reaction, which is not dependent on microorganism actions. Novelty impact statement: The amino acid content in honey samples from Mendoza was determined by high-performance liquid chromatography. Proline and phenylalanine were the more abundant amino acid. Amino acid enantiomeric ratio was assessed by chiral gas chromatography coupled to mass spectrometry. D-amino acids can occur naturally in the honey samples from Mendoza (Argentina). Chemometric tools were applied to discriminate samples from the geographical origin.Fil: Quintas, Pamela Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; ArgentinaFil: Keunchkarian, Sonia. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Laboratorio de Investigación y Desarrollo de Métodos Analíticos. - Comisión de Investigaciones Científicas de la Provincia de Buenos Aires. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; ArgentinaFil: Romero, Lilian. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Laboratorio de Investigación y Desarrollo de Métodos Analíticos. - Comisión de Investigaciones Científicas de la Provincia de Buenos Aires. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; ArgentinaFil: Canizo, Brenda Vanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; ArgentinaFil: Wuilloud, Rodolfo German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Laboratorio de Investigación y Desarrollo de Métodos Analíticos. - Comisión de Investigaciones Científicas de la Provincia de Buenos Aires. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; Argentin

Determination of thermodynamic binding constants by affinity capillary electrophoresis

A strategy to study thermodynamic binding constants by affinity capillary electrophoresis (ACE) is presented. In order to simplify mathematical treatment, analogy with acid-base dissociation equilibrium is proposed: instead of ligand concentration [X], negative logarithm of ligand concentration (or activity), pX = -log[X], is used. On this base, and taking into account ionic activities, a general procedure for obtaining thermodynamic binding constants is proposed. In addition, the method provides electrophoretic mobilities of the free analyte and analyte-ligand complex, even when binding constants are low and thus, the complexed analyte fraction is also low. This is useful as a base to rationally analyze a diversity of situations, i.e., different mathematical dependencies are obtained when analytes and ligands with different charges are combined. Practical considerations are given for carrying out a full experimental design. Enantiomeric ACE separation based on the use of chiral selectors is addressed. 2-hydroxypropyl-β-cyclodextrin was chosen as a model ligand, and both enantiomeric forms of four pharmaceutical drugs (propranolol, pindolol, oxprenolol and homatropine methylbromide) were considered as model analytes. Practical aspects are detailed and thermodynamic binding constants as well as free and complexed analytes mobilities are determined.Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA

Enantioseparation of α-amino acids by means of Cinchona alkaloids as selectors in chiral ligand-exchange chromatography

A conventional nonchiral column was used for the enantioseparation of several racemic a-amino acids (native and derivatized) through the use of Cinchona alkaloids as chiral selectors along with Cu(II) ions in chiral ligand-exchange chromatography. The mobile phase composition (i.e., the organic modifier content and pH) was studied in order to modulate retention and enantioselectivity. Good enantioseparation of many amino acids was obtained using equimolar amounts of Cu(II) and either cinchonidine, quinine or quinidine as chiral selectors in the mobile phase. The molecular geometry of the diastereomeric complexes formed was modeled and energetic differences between both compounds were calculated by methods based on semi-empirical force-field. Good correlations were obtained between experimental enantioselectivity factors and calculated energetic differences.Laboratorio de Investigación y Desarrollo de Métodos AnalíticosCentro de Química InorgánicaCentro de Investigación y Desarrollo en Tecnología de Pintura

Enantiomeric separations by capillary electrophoresis: Theoretical method to determine optimum chiral selector concentration

A method to optimize the ligand concentration [S] in the background electrolyte of capillary electrophoresis separations is presented. It is based on the use of a model which predicts apparent electrophoretic mobilities as a function of ligand concentration (expressed as p[S] = −log[S]). This model is employed to compose the expression of a recently proposed criterion to qualify separations in electrophoresis. Two strategies to find the optimum p[S], leading to the best separation of all compounds, are explained: 1.- a graphical method using a windows map depicting the single separation criteria between all possible combination of compounds by pairs, and 2.- an analytical method where an extended multicriterion optimization function is composed and optimum p[S] is found by mathematical maximization. The procedure is applied to a hard-to-separate model system: enantiomeric separations of racemic mixtures. 2-Hydroxypropyl-β-cyclodextrin was chosen as a model ligand, and four pharmaceutical drugs as model analytes. In order to demonstrate the performance of the procedure, results of electrophoretic separations obtained at p[S] found as optimum are compared with separations obtained at p[S] values slightly higher and lower than the optimum.Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA