Desarrollo de columnas capilares quirales para su empleo en cromatografía de gases: aplicación a la separación de contaminantes ambientales quirales

El objetivo principal de este trabajo de tesis fue el desarrollo de columnas capilares conteniendo fases estacionarias quirales para su uso en cromatografía de gases (CG) que puedan ser usadas en el análisis enantiomérico de múltiples familias químicas de compuestos, principalmente sustancias de interés ambiental. Objetivos específicos: ✓ Desarrollo de columnas capilares conteniendo como fase estacionaria derivados β- y de γ-ciclodextrinas disueltos en un solvente polimérico aquiral y depositados sobre la pared interna del capilar en películas de espesor controlado. ✓ Caracterización de las propiedades cromatográficas de los capilares preparados: eficiencia, selectividad, estabilidad y reproducibilidad. ✓ Medición de constantes de asociación enantiómero/selector a distintas temperaturas. Determinación de la verdadera enantioselectividad sin el uso de hipótesis ad-hoc. Determinación de las propiedades termodinámicas que describen estas asociaciones. ✓ Comparación de las constantes absolutas obtenidas a una dada temperatura con los valores que se obtendrían a partir del modelo de incremento de la retención a la misma temperatura. Evaluación crítica de los resultados. ✓ Estudio de la influencia ejercida por la matriz polimérica aquiral sobre la enantioselectividad aparente para distintos racematos y, eventualmente, en el mecanismo de enantiorreconocimiento. ✓ Aplicación a la separación y análisis enantiomérico de contaminantes ambientales quirales.Facultad de Ciencias Exacta

Enantioseparación de derivados volátiles de aminoácidos por cromatografía de gases empleando una columna quiral de Lipodex E

Los objetivos específicos de este trabajo de tesina son: a- Separar cromatográficamente el mayor número posible de racematos de aminoácidos derivatizados con distintos alquilcloroformiatos mediante una columna quiral para cromatografía de gases conteniendo como selector quiral octakis-(2,6-diO-pentil-3-O-butiril)-γ-ciclodextrina (Lipodex E). b – Evaluar y comparar distintos cloroformiatos de alquilo como agentes derivatizantes de aminoácidos para obtener derivados con mayor volatilidad que puedan ser eluidos a las menores temperaturas posibles en tiempos de análisis razonables; y, simultáneamente, incrementar la señal en el detector de ionización de llama, la cuál aumenta proporcionalmente al número de carbonos en las moléculas eluidas. c.- Optimizar la enantioseparación cromatográfica del mayor número posible de aminoácidos derivatizados por corrida por medio del uso de gradientes de temperatura. d.- Cuantificar los enantiómeros de aminoácidos derivatizados con el/los reactivos más apropiados en muestras de kéfir.Facultad de Ciencias Exacta

Inquiring food practices on the coast of río de la plata through the study of organic waste in ceramic potsherds

In the present paper it is proposed to inquire about the feeding practices of hunter-gatherer and fishermen who inhabited the fluvial coast of Buenos Aires ca. 2000 years. These practices have been studied with different methodologies such as the analysis of microremains in pottery vessel and milling instruments from which wild plant processing tasks have been identified. Morpho-functional aspects have also been worked on the ceramic material through archaeometric techniques recognizing different types of containers with specific functions. In this opportunity the results obtained from the analysis of fatty acids absorbed and adhered in the walls of the archaeological and experimental pottery vessel are presented. The results obtained have been interpreted jointly with the information coming from the archaeofaunal, archaeobotanical and technological record and has allowed to advance in the interpretation of these practices. For this purpose, two archaeological sites have been selected, Las Marias corresponding to the first occupations registered in the area and San Clemente VI belonging to a later occupation. The choice of these sites with different chronologies is based on the interest of analyzing changes and / or continuities in practices related to food processing and environmental management.En el presente trabajo se propone indagar sobre las prácticas alimentarias de los grupos cazadores-recolectores y pescadores que habitaron el litoral fluvial bonaerense hace ca. 2000 años. Estos hábitos han sido estudiados desde diferentes metodologías, tales como el análisis de microrrestos vegetales preservados en tiestos cerámicos e instrumentos de molienda, que han permitido identificar tareas de procesamiento de vegetales silvestres. También se han trabajado aspectos morfo-funcionales a través de técnicas arqueométricas, reconociendo diferentes tipos de vasijas con funciones análisis de ácidos grasos absorbidos y adheridos en las paredes de contenedores cerámicos arqueológicos y experimentales. Estos datos han sido interpretados en forma conjunta con la información procedente del registro arqueofaunístico, arqueobotánico y tecnológico y han permitido avanzar en la interpretación de estas prácticas. Para tal fin se han seleccionado dos sitios arqueológicos: Las Marías, correspondiente a las primeras ocupaciones registradas en la zona, y San Clemente VI, perteneciente a un momento más tardío. La elección de los sitios con cronologías diferentes se fundamenta en el interés de analizar los cambios y/o continuidades en las prácticas vinculadas al procesamiento de alimentos y manejo del entorno.Facultad de Ciencias Naturales y MuseoFacultad de Ciencias Exacta

Inquiring food practices on the coast of río de la plata through the study of organic waste in ceramic potsherds

In the present paper it is proposed to inquire about the feeding practices of hunter-gatherer and fishermen who inhabited the fluvial coast of Buenos Aires ca. 2000 years. These practices have been studied with different methodologies such as the analysis of microremains in pottery vessel and milling instruments from which wild plant processing tasks have been identified. Morpho-functional aspects have also been worked on the ceramic material through archaeometric techniques recognizing different types of containers with specific functions. In this opportunity the results obtained from the analysis of fatty acids absorbed and adhered in the walls of the archaeological and experimental pottery vessel are presented. The results obtained have been interpreted jointly with the information coming from the archaeofaunal, archaeobotanical and technological record and has allowed to advance in the interpretation of these practices. For this purpose, two archaeological sites have been selected, Las Marias corresponding to the first occupations registered in the area and San Clemente VI belonging to a later occupation. The choice of these sites with different chronologies is based on the interest of analyzing changes and / or continuities in practices related to food processing and environmental management.En el presente trabajo se propone indagar sobre las prácticas alimentarias de los grupos cazadores-recolectores y pescadores que habitaron el litoral fluvial bonaerense hace ca. 2000 años. Estos hábitos han sido estudiados desde diferentes metodologías, tales como el análisis de microrrestos vegetales preservados en tiestos cerámicos e instrumentos de molienda, que han permitido identificar tareas de procesamiento de vegetales silvestres. También se han trabajado aspectos morfo-funcionales a través de técnicas arqueométricas, reconociendo diferentes tipos de vasijas con funciones análisis de ácidos grasos absorbidos y adheridos en las paredes de contenedores cerámicos arqueológicos y experimentales. Estos datos han sido interpretados en forma conjunta con la información procedente del registro arqueofaunístico, arqueobotánico y tecnológico y han permitido avanzar en la interpretación de estas prácticas. Para tal fin se han seleccionado dos sitios arqueológicos: Las Marías, correspondiente a las primeras ocupaciones registradas en la zona, y San Clemente VI, perteneciente a un momento más tardío. La elección de los sitios con cronologías diferentes se fundamenta en el interés de analizar los cambios y/o continuidades en las prácticas vinculadas al procesamiento de alimentos y manejo del entorno.Facultad de Ciencias Naturales y MuseoFacultad de Ciencias Exacta

Chiral analysis of derivatized amino acids from kefir by gas chromatography

The amino acids present in the kefir samples were derivatized using different alkyl chloroformates combined with alcohols and chromatographed on a (3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex E) chiral gas-liquid chromatographic column. The combination of derivatization reagents that led to better chromato- graphic performance for standard amino acid solutions was critically compared. All the chloroformate/alchohol mixtures lead to fast and quantitative reactions. However, the ethyl chloroformate/ethanolmixturewas selected since the number of enantioseparated amino acid derivativeswas higher. The derivatizationwas applied to samples of kefir grains grown in raw and in skimmed UHT milk. The samples were previously pretreated by elution froma low-pressure ion-exchange columns. Standard addition calibration curves have been used for the quantitative determinations of amino acid derivatives in both samples, and the figs. of merit of the proposed method have been assessed. The L-and D-configuration of D-and L-alanine, D-and L-valine,D-proline, L-threonine, aspartic and glutamic acids, methionine, and cysteine were detected and quantitatively determined.Fil: Menestrina, Fiorella. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Osorio Grisales, Jaiver. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentin

Determination of gas-liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

In this paper, we report gas-liquid partition constants for thirty-five volatile organic solutes in the room temperature ionic liquid trihexyl(tetradecyl)phosphonium bromide measured by gas-liquid chromatography using capillary columns. The relative contribution of gas-liquid partition and interfacial adsorptionto retention was evaluated through the use of columns with different the phase ratio. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15 K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratioat a given temperature according to the gas-liquid chromatographic theory. Gas-liquid interfacial adsorp-tion was detected for a few solutes and it has been considered for the calculations of partition coefficient.Reliable solute’s infinite dilution activity coefficients can be obtained when retention data are determined by a unique partitioning mechanism. The partial molar excess enthalpies at infinite dilution havebeen estimated from the dependence of experimental values of solute activity coefficients with the column temperature. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA)Comisión de Investigaciones Científicas de la provincia de Buenos Aire

Determination of gas-liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

In this paper, we report gas-liquid partition constants for thirty-five volatile organic solutes in the room temperature ionic liquid trihexyl(tetradecyl)phosphonium bromide measured by gas-liquid chromatography using capillary columns. The relative contribution of gas-liquid partition and interfacial adsorptionto retention was evaluated through the use of columns with different the phase ratio. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15 K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratioat a given temperature according to the gas-liquid chromatographic theory. Gas-liquid interfacial adsorp-tion was detected for a few solutes and it has been considered for the calculations of partition coefficient.Reliable solute’s infinite dilution activity coefficients can be obtained when retention data are determined by a unique partitioning mechanism. The partial molar excess enthalpies at infinite dilution havebeen estimated from the dependence of experimental values of solute activity coefficients with the column temperature. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA)Comisión de Investigaciones Científicas de la provincia de Buenos Aire

Enantioseparation of polar pesticides on chiral capillary columns based on permethyl-β-cyclodextrin in matrices of different polarities

This work describes the influence of different achiral polymers used to dissolve permethyl-β-cyclodextrin (PM-β-CD) on the gas chromatographic enantioresolution of racemic mixtures of polar pesticides (mecoprop, dichlorprop, fenoprop and hydroprop esters, fenoxaprop ethyl, metalaxyl, and haloxyfop esters). One main objective was to introduce a single column for robust and sensitive enantioseparations of several and different polar pesticides, which have to be chromatographed at relatively high temperature (unfavorable condition for enantiodiscrimination). In particular, the ability of capillary columns coated with PM-β-CD dissolved in either (14%-cyanopropylphenyl)(1%-vinyl)-86%-methylpolysiloxane (OV-1701-vi), (5%-phenyl)(1%-vinyl)-95%-methylpolysiloxane (SE-54) or in polyethyleneglycol (Carbowax 20 M), to resolve the racemates of the aforementioned pesticides was evaluated. An analogous commercial column, Hydrodex β-PM, was taken as reference. In addition, the influence of the achiral polymer in the availability of selector for enantioselective interactions with those pesticides was studied. Enantioseparations achieved with the phase based on the less polar polysiloxane SE-54 were higher for most chiral pesticides as compared with those obtained with PM-β-CD mixed in more polar polymers. The results furthermore indicate that a single column based on PM-β-CD/SE-54 exhibited great potential for application in the separation of a wide variety of polar pesticides and their derivatives.Fil: Menestrina, Fiorella. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Ronco, Nicolás Raúl. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Romero, Lílian Mónica. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentin

Determination of gas–liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns

In this paper, we report gas-liquid partition constants for thirty-five volatile organic solutes in the room temperature ionic liquid trihexyl(tetradecyl)phosphonium bromide measured by gas-liquid chromatography using capillary columns. The relative contribution of gas-liquid partition and interfacial adsorption to retention was evaluated through the use of columns with different the phase ratio. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15 K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratio at a given temperature according to the gas-liquid chromatographic theory. Gas-liquid interfacial adsorption was detected for a few solutes and it has been considered for the calculations of partition coefficient. Reliable solute's infinite dilution activity coefficients can be obtained when retention data are determined by a unique partitioning mechanism. The partial molar excess enthalpies at infinite dilution have been estimated from the dependence of experimental values of solute activity coefficients with the column temperature. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.Fil: Ronco, Nicolás Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Menestrina, Fiorella. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Romero, Lílian Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Castells, Cecilia Beatriz Marta. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentin