Chemometrics-assisted excitation–emission fluorescence spectroscopy on nylon-attached rotating disks. Simultaneous determination of polycyclic aromatic hydrocarbons in the presence of interferences

This work presents a green and very simple approach which enables the accurate and simultaneous determination of benzo[a]pyrene, dibenz[a,h]anthracene, benz[a]anthracene, and chrysene, concerned and potentially carcinogenic heavy-polycyclic aromatic hydrocarbons (PAHs) in interfering samples. The compounds are extracted from water samples onto a device composed of a small rotating Teflon disk, with a nylon membrane attached to one of its surfaces. After extraction, the nylon membrane containing the concentrated analytes is separated from the Teflon disk, and fluorescence excitation–emission matrices are directly measured on the nylon surface, and processed by applying parallel factor analysis (PARAFAC), without the necessity of a desorption step. Under optimum conditions and for a sample volume of 25 mL, the PAHs extraction was carried out in 20 min. Detection limits based on the IUPAC recommended criterion and relative errors of prediction were in the ranges 20–100 ng L−1 and 5–7%, respectively. Thanks to the combination of the ability of nylon to strongly retain PAHs, the easy rotating disk extraction approach, and the selectivity of second-order calibration, which greatly simplifies sample treatment avoiding the use of toxic solvents, the developed method follows most green analytical chemistry principles.Fil: Cañas, Alejandro. Universidad de Chile. Facultad de Ciencias Químicas y Farmacéuticas. Departamento de Química Inorgánica y Analítica; Chile.Fil: Richter, Pablo. Universidad de Chile. Facultad de Ciencias Químicas y Farmacéuticas. Departamento de Química Inorgánica y Analítica; Chile.Fil: Escandar, Graciela Mónica. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario (IQUIR-CONICET); Argentina

Non-trilinear chromatographic time retention-fluorescence emission data coupled to chemometric algorithms for the simultaneous determination of 10 polycyclic aromatic hydrocarbons in the presence of interferences

Multivariate calibration coupled to high-performance liquid chromatography-fast scanning fluorescence spectroscopy (HPLC-FSFS) was employed for the analysis of 10 selected polycyclic aromatic hydrocarbons (PAHs), six of which correspond to heavy PAHs. The goal of the present study was the successful resolution of a system even in the presence of real interferences. Second-order HPLC-FSFS data matrices were obtained in a short time with a chromatographic system operating in isocratic mode. The difficulties in aligning chromatographic bands in complex systems, such as the ones presented here, are discussed. Two second-order calibration algorithms which do not require chromatographic alignment were selected for data processing, namely, multivariate curve resolution-alternating least-squares (MCR-ALS) and parallel factor analysis 2 (PARAFAC2). These algorithms did also achieve the second-order advantage, and therefore they were able to overcome the problem of the presence of unexpected interferences. The study was employed for the discussion of the scopes of the applied second-order chemometric tools, demonstrating the superiority of MCRALS to successfully resolve this complex system. The quality of the proposed techniques was assessed on the basis of the analytical recoveries from different types of water and olive oil samples after solid-phase extraction. The studied concentration ranges in water samples were 5.6 × 10-3-0.20 ng mL-1 for heavy PAHs and 0.036-0.80 ng mL-1 for light PAHs, while in oil samples the PAHs concentrations were 0.13-9.6 and 2.3-49.5 ng mL-1 for heavy and light PAHS, respectively. All real samples were analyzed in the presence of the studied interferences.Fil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Arancibia, Juan Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Determination of ochratoxin A in coffee and tea samples by coupling second-order multivariate calibration and fluorescence spectroscopy

A new method to quantify the mycotoxin ochratoxin A (OTA) in coffee and tea samples is proposed based on second-order multivariate calibration and excitation-emission fluorescence matrix (EEFM) data. Experimental conditions were optimized by studying the effect of pH and various organized media on the fluorescence signal of OTA. For each analysed matrix (coffee grains and tea leaves), several sample pretreatments and calibration methods (external or standard addition) and data processing by chemometric models (e.g., parallel factor analysis/PARAFAC and multivariate curve resolution-alternating least squares/MCR-ALS) were evaluated and discussed. The MCR-ALS algorithm provided an adequate fit to the data for both samples, while PARAFAC was satisfactory only for the tea samples. Regarding the figures of merit, the limits of detection were in the range of 0.2–0.3 ng mL−1; furthermore, low relative prediction errors, between 2% and 4%, were achieved in both the fortified and real samples. Accordingly, the proposed methodology was applied to analyse fortified roasted and green coffee and real tea leaf samples. Satisfactory recoveries were achieved (ranging from 92 to 110%), and the obtained concentrations were in agreement with the values obtained by the reference method (based on high-performance liquid chromatography with fluorescence detection/HPLC-FLD). In addition, all samples contained OTA levels lower than the maximum permissible levels. Finally, the proposed strategy allows the use of green analytical chemistry principles; for instance, the use of organic solvents and the generation of waste products were significantly lower than for similar analytical methods reported in the literature.Fil: Gonzalez, Albani L.. Pontificia Universidad Católica de Valparaíso; ChileFil: Lozano, Valeria Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Escandar, Graciela Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Bravo, Manuel A.. Pontificia Universidad Católica de Valparaíso; Chil

Determination of tributyltin at parts-per-trillion levels in natural waters by second-order multivariate calibration and fluorescence spectroscopy

This work presents a non-sophisticated approach for the trace determination of tributyltin, the most toxic organotin species, in very interfering environments, combining fluorescence measurements of its morin complex and the selectivity of second-order chemometric algorithms. The power of MCR–ALS (multivariate curve resolution/alternating least-squares) to quantify tributyltin through fluorescence excitation–emission matrices in the presence of its main degradation products and of a pool of additional twenty-three metal ions is demonstrated. The applied algorithm successfully faces the challenge of solving the strong overlapping among the spectra of the several sample components. The proposed methodology was applied to tap, river, lagoon and seawater spiked samples, obtaining satisfactory results at ngL −1 levels, after a pre-concentration step on a C18 membrane, demonstrating the analytical potential of the proposed methodology.Fil: Bravo, Manuel. Pontificia Universidad Católica de Valparaíso. Instituto de Química. Laboratorio de Química Analítica y Ambiental; Chile.Fil: Aguilar, Luis Felipe. Pontificia Universidad Católica de Valparaíso. Instituto de Química. Laboratorio de Fotofísica y Espectroscopia Molecular; Chile.Fil: Quiroz, Waldo. Pontificia Universidad Católica de Valparaíso. Instituto de Química. Laboratorio de Química Analítica y Ambiental; Chile.Fil: Olivieri, Alejandro César. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario (IQUIR-CONICET); Argentina.Fil: Escandar, Graciela Mónica. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario (IQUIR-CONICET); Argentina

Indagación sobre la noción del “Buen Vivir” en una comunidad originaria de Tartagal, Cherenta

Esta ponencia refiere los marcos teóricos y las observaciones de campo que pusimos en juego para desplegar un trabajo práctico requerido desde la cátedra de Introducción a la Filosofía de la carrera de Comunicación Social de Sede Tartagal de la Universidad Nacional de Salta. El trabajo solicitado requería que observemos la vida cotidiana de una comunidad indígena de la zona, desde la perspectiva de interculturalidad, capitalismo, desarrollo y buen vivir pensadas todas desde la comunicación. Pensamos la interculturalidad como base de la interacción entre sociedades diversas que encuentran espacios comunes generados a través de la comunicación. Los pueblos Esta ponencia refiere los marcos teóricos y las observaciones de campo que pusimos en juego para desplegar un trabajo práctico requerido desde la cátedra de Introducción a la Filosofía de la carrera de Comunicación Social de Sede Tartagal de la Universidad Nacional de Salta. El trabajo solicitado requería que observemos la vida cotidiana de una comunidad indígena de la zona, desde la perspectiva de interculturalidad, capitalismo, desarrollo y buen vivir pensadas todas desde la comunicación. Pensamos la interculturalidad como base de la interacción entre sociedades diversas que encuentran espacios comunes generados a través de la comunicación. Los pueblosEje 9. Historia, memoria y derechos humanosFacultad de Periodismo y Comunicación Socia

Farmacología y terapéutica en medicina interna

Los progresos permanentes en medicina interna y la explosión masiva de la información que hay sobre la misma, exigen de parte de los estudiantes un esfuerzo constante. A pesar de la enorme cantidad de conocimientos enseñados durante la carrera los mismos, con frecuencia, presentan dificultades en recordar información importante y aplicarla en la solución de problemas clínicos relevantes. En el nuevo curriculum médico se hace énfasis en comprender los principios más que en asimilar un conocimiento tras otro. La idea que ha inspirado el nacimiento de estas guías es ofrecer una síntesis para el aprendizaje terapéutico en medicina interna; las mismas son sólo un camino práctico que debe ser complementado con la consulta en los textos correspondientes.Fil: Mema, Escandar.Fil: Sánchez Quintana, Mario.Fil: Mema Marsolie, Cecilia.Fil: Redolfi, Edgardo

Estudio de pre factibilidad para la instalar una planta piloto procesadora de alimentos en el programa Institucional UNI Región Central

Presenta el estudio de pre factibilidad para la instalar una planta piloto procesadora de alimentos en el programa Institucional UNI Región Central en el cual se realizó un estudio de mercado para la determinación de la demanda así como un estudio técnico de localización estratégica, tamaño óptimo, maquinaria y mano de obra

Luminescence Sensors Applied to Water Analysis of Organic Pollutants—An Update

The development of chemical sensors for environmental analysis based on fluorescence, phosphorescence and chemiluminescence signals continues to be a dynamic topic within the sensor field. This review covers the fundamentals of this type of sensors, and an update on recent works devoted to quantifying organic pollutants in environmental waters, focusing on advances since about 2005. Among the wide variety of these contaminants, special attention has been paid polycyclic aromatic hydrocarbons, pesticides, explosives and emerging organic pollutants. The potential of coupling optical sensors with multivariate calibration methods in order to improve the selectivity is also discussed

Standard addition method based on four-way PARAFAC decomposition to solve the matrix interferences in the determination of carbamate pesticides in lettuce using excitation–emission fluorescence data

The simultaneous determination of two carbamate pesticides (carbaryl and carbendazim) and of the degradation product of carbaryl (1-naphthol) in iceberg lettuce was achieved by means of PARAFAC decomposition and excitation–emission fluorescence matrices. A standard addition method for a calibration based on four-way data was applied using different dilutions of the extract from iceberg lettuce as a fourth way that provided the enough variation of the matrix to carry out the four-way analysis. A high fluorescent overlapping existed between the three analytes and the fluorophores of the matrix. The identification of two fluorescent matrix constituents through the four-way model enabled to know the matrix contribution in each dilution of the extract. This contribution was subtracted from the previous signals and a subsequent three-way analysis was carried out with the tensors corresponding to each dilution. The PARAFAC decomposition of these resulting tensors showed a CORCONDIA index equal to 99%. For the identification of the analytes, the correlation between the PARAFAC spectral loadings and the reference spectra has been used. The trueness of the method, in the concentration range studied, was guaranteed because there was neither constant nor proportional bias according to the appropriate hypothesis tests. The best recovery percentages were obtained with the data from the most diluted extract, being the results: 127.6% for carbaryl, 125.55% for carbendazim and 87.6% for 1-naphthol. When the solvent calibration was performed, the decision limit (CCα) and the capability of detection (CCβ) values, in x0=0, were 2.21 and 4.38 μg L−1 for carbaryl, 4.87 and 9.64 μg L−1 for carbendazim; and 3.22 and 6.38 μg L−1 for 1-naphthol, respectively, for probabilities of false positive and false negative fixed at 0.05. However, these values were 5.30 and 10.49 μg L−1 for carbaryl, 18.05 and 35.73 μg L−1 for carbendazim; and 1.92 and 3.79 μg L−1 for 1-naphthol, respectively, when the matrix-matched calibration using the most diluted extract was carried out in the recovery study.Ministerio de Economía y Competitividad(CTQ2011-26022) and JuntadeCastillayLeón(BU108A11-2)