51 research outputs found
Second-order calibration in combination with fluorescence fibre-optic data modelling as a novel approach for monitoring the maturation stage of plums
In this work, non-destructive autofluorescence of plums was employed to study the chlorophylls’ concentration evolution along the maturation process. For that, excitation-emission matrices (EEMs), containing full fluorescence information, were collected with a fibre-optic, assembled to a spectrofluorometer. Data analysis was performed with several second-order multi-way algorithms, such as parallel factor analysis (PARAFAC), multi-way partial least-squares (N-PLS), unfolded partial least-squares (U-PLS), and multivariate curve resolution-alternating least-squares (MCR-ALS). Firstly, the EEMs of each plum, collected each week along the maturation process, were processed with PARAFAC. Two components were used to model the data and the excitation and emission loadings were obtained. Score values for the first PARAFAC component showed a clear evolution with time, increasing during the first five weeks, and decreasing for the last weeks. Also, the chlorophyll concentrations obtained by HPLC analysis, in the skin and the whole fruit, were compared with those obtained with different algorithms mentioned before. Best results were obtained in the case of skin for all algorithms. Similar correlation coefficients (r) were obtained in all cases (0.899 (PARAFAC); 0.940 (U-PLS); 0.936 (N-PLS) and 0.958 (MCR-ALS)). When the elliptical joint confidence region (EJCR), for the slope and intercept, were calculated, the theoretically expected values of 1 and 0, for the slope and intercept, respectively, were included in all ellipses. However, it was observed that for the skin data and U-PLS and N-PLS algorithms, the EJCR confidence region was smaller than in the other cases.submittedVersio
Potential Fields as an External Force and Algorithmic Improvements in Deformable Models
Deformable Models are extensively used as a Pattern Recognition technique. They are curves defined within an image domain that can be moved under the influence of internal and external forces. Some trade-offs of standard deformable models algorithms are the selection of image energy function (external force), the location of initial snake and the attraction of contour points to local energy minima when the snake is being deformed. This paper proposes a new procedure using potential fields as external forces. In addition, standard Deformable Models algorithm has been enhanced with both this new external force and algorithmic improvements. The performance of the presented approach has been successfully proved to extract muscles from Magnetic Resonance Imaging (MRI) sequences of Iberian ham at different maturation stages in order to calculate their volume change. The main conclusions of this paper are the practical viability of potential fields used as external forces, as well as the validation of the algorithmic improvements developed. The feasibility of applying Computer Vision techniques, in conjunction with MRI, for determining automatically the optimal ripening time of the Iberian ham is a practical conclusion reached with the proposed approach
Applying multivariate curve resolution modelling combined with discriminant tools on near-infrared spectra for distinguishing between cheese varieties and stages of ripening
In this study, near-infrared (NIR) spectra were employed to monitor the ripening process of two kinds of soft cheese produced in the Extremadura region of Spain, manufactured by two different producers, “Torta del Casar” and “Queso de la Serena”. Spectra were collected from the interior of the cheeses and the rind and analysed using appropriate chemometric techniques to distinguish between the two varieties and among different weeks of the maturation process. Different chemometric tools, including multivariate curve resolution with alternating least squares (MCRALS), linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), and feed-forward artificial neural networks (FF-ANN), were utilised, resulting in outstanding discrimination outcomes with sensitivity, precision, specificity, and accuracy reaching values c.a. 1.00 in optimal scenarios. More comprehensive information was acquired from the rind spectra analysis, indicating that the sampling process can be performed without disturbing the cheese in a non-destructive way. Remarkably, the capability to distinguish between various weeks of ripening for both cheeses could enable manufacturers to produce market-ready products earlier than the typically established timeline.Fil: MartĂn Tornero, ElĂsabet. Universidad de Extremadura; EspañaFil: Durán Merás, Isabel. Universidad de Extremadura; EspañaFil: Alcaraz, Mirta Raquel. Universidad Nacional del Litoral. Facultad de BioquĂmica y Ciencias BiolĂłgicas. Laboratorio de Desarrollo AnalĂtico y QuimiometrĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Muñoz de la Peña, Arsenio. Universidad de Extremadura; EspañaFil: Galeano DĂaz, Teresa. Universidad de Extremadura; EspañaFil: Goicoechea, Hector Casimiro. Universidad Nacional del Litoral. Facultad de BioquĂmica y Ciencias BiolĂłgicas. Laboratorio de Desarrollo AnalĂtico y QuimiometrĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; Argentin
Analysis of Monosodium l-Glutamate in Food Products by High-Performance Thin Layer Chromatography
A simple, fast, specific, and precise high-performance thin layer chromatography method has been developed for the estimation of monosodium l-glutamate (MSG) in food products. Aluminum plates precoated with silica gel 60 GF254were used as stationary phase and a mixture of methanol–chloroform–formic acid in the ratio 5:5:1 (v/v) as mobile phase. Quantification was carried out by postchromatographic derivatization using 1% ninhydrin solution, and the developed spots were scanned by using a densitometer in absorbance mode at 485 nM. The Rfvalue of MSG was 0.64. The results of the analysis have been validated statistically and by the recovery studies. Linearity was observed in the concentration range of 400–1000 nG
Selective complexation of divalent cations by a cyclic α,β-peptoid hexamer: a spectroscopic and computational study
We describe the qualitative and quantitative analysis of the complexation properties towards cations of a cyclic peptoid hexamer composed of alternating α- and β-peptoid monomers, which bear exclusively chiral (S)-phenylethyl side chains (spe) that have no noticeable chelating properties. The binding of a series of monovalent and divalent cations was assessed by 1H NMR, circular dichroism, fluorescence and molecular modelling. In contrast to previous studies on cations binding by 18-membered α-cyclopeptoid hexamers, the 21-membered cyclopeptoid cP1 did not complex monovalent cations (Na+, K+, Ag+) but showed selectivity for divalent cations (Ca2+, Ba2+, Sr2+ and Mg2+). Hexacoordinated C-3 symmetrical complexes were demonstrated for divalent cations with ionic radii around 1 Å (Ca2+ and Ba2+), while 5-coordination is preferred for divalent cations with larger (Ba2+) or smaller ionic radii (Mg2+)
Green analytical determination of emerging pollutants in environmental waters using excitation-emission photoinduced fluorescence data and multivariate calibration
An eco-friendly strategy for the simultaneous quantification of three emerging pharmaceutical contaminants is presented. The proposed analytical method, which involves photochemically induced fluorescence matrix data combined with second-order chemometric analysis, was used for the determination of carbamazepine, ofloxacin and piroxicam in water samples of different complexity without the need of chromatographic separation. Excitation-emission photoinduced fluorescence matrices were obtained after UV irradiation, and processed with second-order algorithms. Only one of the tested algorithms was able to overcome the strong spectral overlapping among the studied pollutants and allowed their successful quantitation in very interferent media. The method sensitivity in superficial and underground water samples was enhanced by a simple solid-phase extraction with C18 membranes, which was successful for the extraction/preconcentration of the pollutants at trace levels. Detection limits in preconcentrated (1:125) real water samples ranged from 0.04 to 0.3 ng mL?1. Relative prediction errors around 10 % were achieved. The proposed strategy is significantly simpler and greener than liquid chromatography-mass spectrometry methods, without compromising the analytical quality of the results.Fil: Hurtado-Sánchez, MarĂa del Carmen. Universidad de Extremadura. Departamento de QuĂmica AnalĂtica; España.Fil: Lozano, Valeria A. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de QuĂmica AnalĂtica. Instituto de QuĂmica de Rosario (IQUIR-CONICET); ArgentinaFil: Lozano, Valeria A. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de QuĂmica AnalĂtica. Instituto de QuĂmica de Rosario (IQUIR-CONICET); ArgentinaFil: RodrĂguez-Cáceres, MarĂa Isabel. Universidad de Extremadura. Departamento de QuĂmica AnalĂtica; España.Fil: Durán-Merás, Isabel. Universidad de Extremadura. Departamento de QuĂmica AnalĂtica; España.Fil: Escandar, Graciela M. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Departamento de QuĂmica AnalĂtica. Instituto de QuĂmica de Rosario (IQUIR-CONICET); Argentina
Fluorescence Monitoring Oxidation of Extra Virgin Olive Oil Packed in Different Containers
‘Picual’ olive oil was stored in different types of containers for 10 months and monitored via quality parameters. In combination with the mentioned analysis, non-destructive fluorescence spectroscopy was performed combined with multivariate analysis to monitor and quantify oil quality levels. Excitation emission matrices (EMMs) were analyzed using parallel factor analysis (PARAFAC). According to the quality parameters, it was observed that Transparent Crystal (TC) and Opaque Crystal (OC) samples were the ones that deteriorated faster due to their higher exposure to light in comparison with Plastic (P) and Canned (C) samples. In a fast and non-destructive manner, the fluorescence spectroscopy-based prototype successfully monitored the oxidation changes in the EVOOs. Unfolded partial least squares (U-PLS) was used to generate a regression model to quantify quality parameters. Good correlation coefficients were found for the peroxide index, K232 and the oxidative stability index (r2 between 0.90 and 0.94 for cross-validation and validation). For all of that, the results obtained confirmed the ability of fluorescence spectroscopy to monitor the quality of olive oil and EEMs combined with U-PLS can be used to analyze these parameters, eluding the classical methods
Development of an HPLC-MS method for the determination of natural pteridines in tomato samples
En las plantas, las pteridinas reducidas son intermedios de la biosĂntesis de folato, y la presencia de estos analitos en los procesos de biofortificaciĂłn se considera crucial. Se optimizĂł un mĂ©todo simple de cromatografĂa lĂquida-espectrometrĂa de masas (LC-ESI-MS) para la determinaciĂłn de pteridinas naturales en muestras de tomate. Se ha empleado una etapa de extracciĂłn en fase sĂłlida (SPE) usando cartuchos ISOLUTE ENV para limpiar las muestras. Once pteridinas han sido analizadas pero solo cuatro de ellas han sido detectadas y cuantificadas en tomates. La estabilidad de las pteridinas e hidropteridinas en extractos de tomate ha sido estudiada. Se evaluaron los parámetros de validaciĂłn y se obtuvo una buena linealidad ( R 2 > 0,99 en todos los casos) y precisiĂłn (los valores de la desviaciĂłn estándar relativa interdĂa fueron inferiores al 10%).Las cantidades (como ÎĽg por g de muestra fresca) encontradas de cada pteridina fueron 0,019, 0,44, 0,043 y 0,087 para neopterina, 7,8-dihidroneopterina, 6-hidroximetilpterina y ácido pterin-6-carboxĂlico, respectivamenteIn plants, reduced pteridines are folate biosynthesis intermediates, and the presence of these analytes in biofortification processes is considered crucial. A simple liquid chromatography-mass spectrometry (LC-ESI-MS) method has been optimized for the determination of natural pteridines in tomato samples. A solid phase extraction (SPE) step using ISOLUTE ENV cartridges has been employed for cleaning up the samples. Eleven pteridines have been assayed but only four of them have been detected and quantified in tomatoes. The stability of the pteridines and hydropteridines in tomato extracts has been studied. Validation parameters have been evaluated and good linearity (R2 > 0.99 in all cases) and precision (interday relative standard deviation values were lower than 10%) were obtained. The amounts (as ÎĽg per g of fresh sample) found of each pteridine were 0.019, 0.44, 0.043 and 0.087 for neopterin, 7,8-dihydroneopterin, 6-hydroxymethylpterin and pterin-6-carboxylic acid, respectively.Trabajo financiado por:
Ministerio de EconomĂa y Competitividad. Proyecto CTQ2014-52309-P
Ministerio de EconomĂa y Competitividad y Fondos Sociales Europeos para FPI. Ayuda BES-2015-075407, para ElĂsabet MartĂn Tornero
Junta de Extremadura y Fondos FEDER. Ayuda GR15090- Grupos de InvestigaciĂłn FQM003peerReviewe
An optimized methodology for the determination of multiclass organic ultraviolet sunscreens and metabolites in human milk through chromatographic and chemometric resolution
Organic UV filters (UVFS) are used to mitigate the dermal effects associated with health risks from UV radiation, making them essential in personal care products. UVFS are frequently identified in environmental samples due to their high lipophilicity and persistence, underscoring the urgency of comprehensive assessments and regulatory measures aimed at safeguarding ecosystems and human health. The present study reports a multiclass analytical method for determining 16 UV sunscreens and metabolites in breast milk based on an ultrasound-assisted-dispersive liquid-liquid micro-extraction (UA-DLLME) with further chromatographic and chemometric resolution. The experimental conditions of the UA-DLLME were optimized through the implementation of the Design of Experiment tools. To model the responses, least-squares and artificial neural network methodologies were implemented. The optimal conditions were found by employing the desirability function. The samples were analyzed through reverse-phase liquid chromatographic separation, UV diode array, and fast-scanning fluorescence detection. The chromatographic analysis enabled the resolution of 16 analytes in a total time of 13.0 min. Multivariate curve resolution-alternating least-square (MCR-ALS) modelling was implemented to resolve analytes that were not fully resolved and to determine analytes that coeluted with endogenous components of the breast milk samples. An enrichment factor of 5-fold concentration was obtained with this methodology, reaching recoveries between 65 % and 105 % for 13 multiclass UV sunscreens and metabolites in breast milk samples with RSD % and REP % lower than 12 %.Fil: Alcaraz, Mirta Raquel. Universidad Nacional del Litoral. Facultad de BioquĂmica y Ciencias BiolĂłgicas. Laboratorio de Desarrollo AnalĂtico y QuimiometrĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Espinosa Mansilla, AnunciaciĂłn. Universidad de Extremadura; EspañaFil: Durán Merás, Isabel. Universidad de Extremadura; EspañaFil: Muñoz de la Peña, Arsenio. Universidad de Extremadura; Españ
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