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

Evaluation of photo-induced crosslinking of thymine polymers using FT-IR spectroscopy and chemometric analysis

The photo-induced immobilization of 4-vinylbenzyl thymine (VBT) and 4-vinylbenzyl triethyl ammonium chloride (VBA) copolymers has been investigated with the aid of grazing-angle specular-reflectance FT-IR spectroscopy. As irradiation time increases, changes in the structure of pendent thymine groups in the copolymer due to the crosslinking process result in shifts of the copolymer network’s vibrational frequencies, as well as changes in numerous IR band intensities. In this work, chemometric methods have been applied to the FT-IR data obtained while monitoring the time evolution of curing of VBT-VBA copolymers of varying composition. The spectral data obtained with FT-IR normally provide information only about the degree of conversion of the reactants in the final product but there is no knowledge about how many compounds are involved or how they evolve over time. The use of the so-called Multivariate Curve Resolution-Alternating Least Squares allows the sequential estimation of the contribution to the signal due to the different species in the matrix data.Fil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Thomas, Katelyn. Simmons College; Estados UnidosFil: Mcdonough, Kristin. Simmons College; Estados UnidosFil: Gurney, Richard. Simmons College; Estados UnidosFil: Martino, Debora Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Multivariate analysis of organic acids in fermented food from reversed-phase high-performance liquid chromatography data

Multivariate calibration coupled to RP-HPLC with diode array detection (HPLC-DAD) was applied to the identification and the quantitative evaluation of the short chain organic acids (malic, oxalic, formic, lactic, acetic, citric, pyruvic, succinic, tartaric, propionic and α-cetoglutaric) in fermented food. The goal of the present study was to get the successful resolution of a system in the combined occurrence of strongly coeluting peaks, of distortions in the time sensors among chromatograms, and of the presence of unexpected compounds not included in the calibration step. Second-order HPLC-DAD data matrices were obtained in a short time (10 min) on a C18 column with a chromatographic system operating in isocratic mode (mobile phase was 20 mmol L−1 phosphate buffer at pH 2.20) and a flow-rate of 1.0 mL min−1 at room temperature. Parallel factor analysis (PARAFAC) and unfolded partial least-squares combined with residual bilinearization (U-PLS/RBL) were the second-order calibration algorithms select for data processing. The performance of the analytical parameters was good with an outstanding limit of detection (LODs) for acids ranging from 0.15 to 10.0 mmol L−1 in the validation samples. The improved method was applied to the analysis of many dairy products (yoghurt, cultured milk and cheese) and wine. The method was shown as an effective means for determining and following acid contents in fermented food and was characterized by reducibility with simple, high resolution and rapid procedure without derivatization of analytes.Fil: Mortera, Pablo. 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: Zuljan, Federico Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Magni, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: 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: Alarcon, Sergio Hugo. 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

Novel polybenzoxazine and polybenzoxazine/epoxy thermosetting copolymers containing polysilsesquioxane nanostructures for high-performance thermal protection systems

This work focuses on the development of novel thermosetting systems derived from a siloxane-based benzoxazine hybrid precursor [Pr(BA-3aptms)], a conventional benzoxazine (BA-a) and a commercial epoxy resin (DGEBA) based on bisphenol A, as a strategy to prepare benzoxazine/benzoxazine and epoxy/benzoxazine copolymers with different amounts of polysilsesquioxanes in their chemical structure. The effect of the siloxane composition on the morphology was investigated, and their influence on the thermal, dynamo-mechanical and flammability properties was elucidated. The obtained results allowed to conclude that an increase of the BA-a or DGEBA content in the copolymers, considerably affects the morphology of the materials. In this sense, the laminar arrangement changed to a nanocluster arrangement when the contents of Si were below 17% w/w for the epoxy/benzoxazine and below 10% w/w for benzoxazine/benzoxazine systems, respectively. Also, the thickness of the organic sheets in the matrices was increased when increasing the content of BA-a or DGEBA in the materials. In addition, the incorporation of the polysilsesquioxane-based precursor in the crosslinked materials improved the investigated properties, such as: thermal, mechanical and flame resistance, and hydrophobic behavior.Fil: Forchetti Casarino, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Bortolato, Santiago Andres. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Analítica; Argentina. 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: Casis, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Estenoz, Diana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Spontón, Marisa Elisabet. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Photo-induced curing of thymine-based bioinspired polymers. A chemometric analysis

The curing process of new materials based on styrene monomers functionalized with thymine and charged ionic groups was studied using UV-vis spectroscopy in combination with chemomet-ric models. The effect of the copolymer molecular weight on the immobilization point was analyzed. The evolution of the curing process of the copolymer (4-vinylbenzyl) thymine (VBT) -vinylbenzyl triethyl ammonium chloride (VBA) involved three species, which absorb in the spectral region analyzed. The contributions of each species to the total signal at each irradiation time were determined, and the ki-netic constant of the crosslinking reaction was esti-mated. The study allowed evaluating the consistency of the chemometric decomposition, obtaining a rea-sonable correlation between the frequency spectra and the time evolution calculated with the algorithm. The chemometric analysis showed to be a powerful tool to provide complementary information on photo-induced immobilization of VBT-VBA films, which is crucial for developing new environmentally benign materials and new energy-saving methods.Fil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Salta. Instituto de Investigación para la Industria Química (i); ArgentinaFil: Barbarini, Alejandro Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Salta. Instituto de Investigación para la Industria Química (i); ArgentinaFil: Benitez, R. M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Salta. Instituto de Investigación para la Industria Química (i); ArgentinaFil: Martino, Debora Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Salta. Instituto de Investigación para la Industria Química (i); ArgentinaFil: Estenoz, Diana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Salta. Instituto de Investigación para la Industria Química (i); Argentin

New insights into the analysis of red blood cells from leukemia and anemia patients: Nonlinear quantifiers, fractal mathematics, and Wavelet Transform

The alterations of red blood cells (RBCs) membrane in many hematological diseases prevent blood to accomplish its functions, but how these alterations occur is not completely understood. Hence, the development of a simple and accurate methodology for the characterization of different populations of RBCs is necessary for hematology and clinical diagnosis. In this work, we focus on different pathologies that affect the hemorheological properties of human beings blood. The results were obtained by studying healthy individuals, anemia and leukemia patient samples. Data analysis involved the use of non-linear methods, based on two different analytical strategies. On one hand, we used nonlinear mathematical quantifiers (False Nearest Neighbors, Embedding Dimension, May–Sugihara Correlation, and Hurst Exponent) on ektacytometrically recorded time series measuring the elongation of re-suspended RBCs subjected to well-defined shear stress. On the other hand, we developed an analytical methodology to aid in the diagnosis of those pathologies, based on the box-counting dimension from digital images of cells suspensions that were denoised standardly by application of Wavelet Transform. The results allowed preliminary discrimination of different populations studied and a correlation with its membrane damage.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: Mancilla Canales, Manuel Arturo. Universidad Nacional de Rosario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Riquelme, Bibiana Doris. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Raviola, Mariana Paula. Universidad Nacional de Rosario; ArgentinaFil: Leguto, Alcides José. Universidad Nacional de Rosario; ArgentinaFil: Rebechi, Juan Pablo. Universidad Nacional de Rosario; ArgentinaFil: Ponce de León, Patricia Carolina. Universidad Nacional de Rosario; ArgentinaFil: Korol, Ana María. Universidad Nacional de Rosario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Functional data analysis, a new approach to aligning three-way liquid chromatographic with fluorescence detection data

Functional data analysis (FDA) arises as a promissory auxiliary methodology designed to help the analytical chemists, especially chemometricians. However, although the innovative ideas of this approach have barely spread into the chemical research field. In this work, a novel approach for aligning three-way chromatographic-spectral data based on FDA methodology is proposed. Unlike most of the available algorithms, this novel method allows performing data alignment when the test data matrix contains unexpected chemical interferences. Simulated and experimental analytical systems composed of calibrated analytes and potential interferents in the test samples are studied. The experimental system corresponds to the determination of the four polycyclic aromatic hydrocarbons (benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[b]fluoranthene and benzo [k]fluoranthene) in the presence of benzo[j]fluoranthene and benzo[e]pyrene as potential interferences. These compounds are priority pollutants; hence, its reliable quantification in environmental samples is an analytical challenge. The method consists in decomposing the three-way data in each sensor mode and in making a functional alignment of the pure vectors obtained from the individual chromatograms of each analyte and interferent. The functional preprocessing step enables the analysis of the data set with second-order multivariate calibration algorithms, such as PARAFAC. The results illustrate that the proposed method restores the trilinearity of the three-way data, thus being able to successfully quantify the analytes in the presence of the interferences, that is, exploiting the second-order advantage. MCR-ALS is also applied to both simulated and experimental data to evaluate the performance of the PARAFAC second-order calibration model proposed. The performance of the PARAFAC and MCR-ALS models are compared and discussed.Fil: Lombardi, Juan Manuel. 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: 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; Argentin

Chemometric processing of second-order liquid chromatographic data with UV-vis and fluorescence detection. A comparison of multivariate curve resolution and parallel factor analysis 2

Second-order liquid chromatographic data with multivariate spectral (UV?vis or fluorescence) detection usually show changes in elution time profiles from sample to sample, causing a loss of trilinearity in the data. In order to analyze them with an appropriate model, the latter should permit a given component to have different time profiles in different samples. Two popular models in this regard are multivariate curve resolution-alternating least-squares (MCR-ALS) and parallel factor analysis 2 (PARAFAC2). The conditions to be fulfilled for successful application of the latter model are discussed on the basis of simple chromatographic concepts. An exhaustive analysis of the multivariate calibration models is carried out, employing both simulated and experimental chromatographic data sets. The latter involve the quantitation of benzimidazolic and carbamate pesticides in fruit and juice samples using liquid chromatography with diode array detection, and of polycyclic aromatic hydrocarbons in water samples, in both cases in the presence of potential interferents using liquid chromatography with fluorescence spectral detection, thereby achieving the second-order advantage. The overall results seem to favor MCR-ALS over PARAFAC2, especially in the presence of potential interferents.Fil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Olivieri, Alejandro Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; Argentin

Evolution of erythrocytes aggregation: A fractal approach when incubated with Trichinella spiralis and Ascaris lumbricoides

Fractal geometry has provided a new range of concepts that could explain the non-linear behaviour of seemingly unpredictable natural systems. The aim of this work is to apply nonlinear analysis to study the . in vitro erythrocyte aggregation produced by incubation of human red blood cells (RBCs) with . Ascaris lumbricoides and also . Trichinella spirallis larvae extracts. The approach used was based on calculating the fractal slope (D), through image processing of control and treated RBCs at different incubation times (200 images). The results showed a decrease in the fractal dimension value of . Ascaris lumbricoides treated RBCs (up to 10%) and a constant value of D in the case of . Thichinella spiralis treated RBCs, in contrast to a more disperse value showed in normal controls. This modification in the D might be correlated with the different actions of each parasite over the erythrocyte membrane leading to abnormal RBCs aggregation.Fil: Lupo, Maela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Médicas; ArgentinaFil: Leguto, Alcides José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Korol, Ana María. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentin

Modelado Matemático de la Reacción de Curado de Copolímeros Bioinspirados

En este trabajo se estudia la reacción de entrecruzamiento fotoinducido de copolímeros sintéticos bioinspirados basados en timina y grupos iónicos . Se desarrolla un modelo matemático para el proceso de curado basado en técnicas estadísticas que se acopla a la cinética de entrecruzamiento para predecir la evolución del grado de entrecruzamiento en función del tiempo de curado, y los tiempos de gel en función de la estructura molecular del polímero y de las condiciones de curado. Los resultados teóricos se comparan con mediciones por espectroscopía de absorción UV.Fil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: D.m. Martino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: C. Sarmoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin