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Monago Maraña, Olga

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2016 - 20173
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Autor: Muñoz de la Peña, Arsenio × search.filters.applied.f.itemFacultad: Facultad de Ciencias ×

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Mostrando 1 - 3 de 3
  • Miniatura
    Publicación
    Determination of Quercetin and Luteolin in Paprika Samples by Voltammetry and Partial Least Squares Calibration
    (Wiley, 2017-09-19) Chamizo González, Francisco; Galeano Díaz, Teresa; Muñoz de la Peña, Arsenio; Monago Maraña, Olga
    Quercetin and luteolin are flavonoids with beneficious properties, which are present in paprika. In this work, both have been determined in paprika by using electrochemistry combined with chemometrics. The electrochemical oxidation mechanisms of both analytes have been studied through sampled direct current (DC) voltammetry, differential pulse voltammetry (DPV) and Square Wave Voltammetry (SWV), making use of a glassy carbon electrode. The final technique selected for the quantification was DPV due to its high repeatability with respect SWV. The chemical variables and the instrumental parameters were optimized and the final conditions employed were ethanol: water (20 : 80), 0.75 mol dm−3 of HCl, and a pulse amplitude of 50 mV. Due to the facts that oxidation potential of both analytes were quite similar, their DPV peaks were overlapped, and also because the analytes interaction during the electrochemical process causes a non-additivity of the signals, they could not be quantified separately by direct measurement of peak intensity. For this reason, a chemometric algorithm was applied (partial least squares (PLS) regression in its modality PLS-2). In the case of validation samples, appropriate sets of calibration and validation were built and good results were obtained. This methodology was applied to real paprika samples and the results were similar to those obtained with a HPLC method previously reported.
  • Miniatura
    Publicación
    Isocratic LC–DAD–FLD method for the determination of flavonoids in paprika samples by using a rapid resolution column and post-column pH change
    (Elsevier, 2016-05-15) Galeano Díaz , Teresa; Muñoz de la Peña, Arsenio; Monago Maraña, Olga
    The determination of flavonoid compounds in paprika samples has been performed by liquid chromatography in series diode array and fluorescence detection (LC–DAD–FLD), by means of a pH change to basic medium just before FLD detection. The validation of the method was performed through the establishment of the external standard calibration curves and the analytical figures of merit. Limits of detection ranging from 0.006 to 0.02 mg L−1 and 0.007 to 0.09 mg L−1 were achieved using DAD and FLD detection, respectively. The experimental conditions to carry out the hydrolysis procedure to obtain flavonoid aglycones from flavonoid glycosides have been optimized applying an experimental design and the response surface methodology. The final conditions selected were 2.5 M HCl during 45 min at 85 °C. The repeatability of this procedure was assayed and relative standard deviation (RSD) values for concentration of quercetin and luteolin compounds were lower than 2%. The quantification of quercetin, luteolin and kaempferol compounds was carried out in less than 6 min in paprika samples by means of the external standard calibration. The analytes were extracted with methanol and the extracts were previously subjected to a cleanup procedure to extend the use of the chromatographic column.
  • Miniatura
    Publicación
    Combination of Liquid Chromatography with Multivariate CurveResolution-Alternating Least-Squares (MCR-ALS) in the Quantitationof Polycyclic Aromatic Hydrocarbons Present in Paprika Samples
    (American Chemical Society, 2016-10-07) Pérez, Rocío L; Escandar, Graciela M.; Muñoz de la Peña, Arsenio; Galeano Díaz, Teresa; Monago Maraña, Olga
    This work presents a strategy for quantitating polycyclic aromatic hydrocarbons (PAHs) in smoked paprikasamples. For this, a liquid chromatographic method withfluorimetric detection (HPLC-FLD) was optimized. To resolve some interference co-eluting with the target analytes, the second-order multivariate curve resolution-alternating least-squares (MCR-ALS) algorithm has been employed combined with this liquid chromatographic method. Among the eight PAHs quantified(fluorene, phenanthrene, anthracene, pyrene, chrysene, benzo[a]anthracene, benzo[b]fluoranthene, and benzo[a]pyrene) byHPLC-FLD, only in the case offluorene, pyrene, and benzo[b]fluoranthene was it necessary to apply the second-order algorithmfor their resolution. Limits of detection and quantitation were between 0.015 and 0.45 mg/kg and between 0.15 and 1.5 mg/kg,respectively. Good recovery results (>80%) for paprika were obtained via the complete extraction procedure, consisting of anextraction from the matrix and the cleanup of the extract by means of silica cartridges. Higher concentrations of chrysene,benzo[a]anthracene, benzo[b]fluoranthene, and benzo[a]pyrene were found in the paprika samples, with respect to the maximalamounts allowed for other spices that are under European Regulation (EU) N°2015/1933