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Monago Maraña, Olga

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olgamonago@ccia.uned.es
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Monago Maraña
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2016 - 201992020 - 202515
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Mostrando 1 - 10 de 24
  • Miniatura
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    Non-destructive fluorescence spectroscopy combined with second-order calibration as a new strategy for the analysis of the illegal Sudan I dye in paprika powder
    (Elsevier, 2020-05) Eskildsen, Carl Emil; Muñoz de la Peña, Arsenio; Galeano Díaz, Teresa; Wold, Jens Petter; Monago Maraña, Olga
    This paper presents a novel strategy for determination of the illegal dye Sudan I in paprika powder. The method is based on fluorescence spectroscopy combined with second-order calibration, which was employed for the first time for this purpose. The method is non-destructive and requires no sample preparation. It was probed that Sudan I exhibited fluorescence; however, the color of paprika samples affected the signal and it was not possible to quantify this adulterant by means of univariate and first-order calibration. To model the effect of variability of color in samples, a central composite experimental design was performed with varying ASTA (American Spices Trade Association) color values and Sudan I concentrations. Different second-order algorithms were tried for quantification. The best results for calibration and validation were obtained from Unfolded-Partial Least-Squares (U-PLS) and Multi-way Partial Least-Squares (N-PLS). The level of detection ranges were 0.4 – 3 mg/g and 0.5 – 3 mg/g for U-PLS and N-PLS, respectively. This was lower than other methods found in the literature.
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    Preclinical Validation of an Electrochemical Sensor for Alcohol Consumption Monitoring in a Polydrug Self-Administration Animal Model
    (MDPI, 2025-03-08) Garrido Matilla, Lucía; María Hormigos, Roberto; Monago Maraña, Olga; Marcos, Alberto; Ambrosio Flores, Emilio; González Crevillén, Agustín
    An electrochemical sensor for identification and monitoring of alcoholism was preclinically validated by analyzing plasma from polydrug-consuming rats (alcohol and cocaine). The sensor measures by adsorptive transfer square wave voltammetry the glycosylation level of transferrin, which is an alcoholism biomarker, through a recently reported parameter called the electrochemical index of glycosylation (EIG). Three rat groups were designed: saline group, cocaine group, and cocaine–alcohol group. Moreover, two periods of withdrawal were studied, after 2 days and 30 days. The alcohol–cocaine group after 2 days of withdrawal showed significantly lower EIG values (p < 0.1) than the rest of groups and also alcohol–cocaine group after 30 days of withdrawal, so the sensor was able to identify the alcohol consumption in rats and to monitor the recovery of glycosylation level after 30 days of withdrawal, even combined with cocaine. Furthermore, the effect of sex was also considered. Receiver operating characteristic (ROC) curves were developed for each sex and the corresponding cut-off values were determined. The sensor showed a clinical sensitivity of 70% for male and 75% for female, and a specificity of 67% for both sexes. This preclinical validation demonstrated the possibilities of this sensor for point of care testing of alcoholism, even in cocaine addicts, making it a potential tool for diagnosis and monitoring of alcohol consumption in detox treatments for humans.
  • Miniatura
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    Wearable sensor for solar ultraviolet A radiation monitoring based on a basic bismuth nitrate / graphene quantum dots composite
    (Elsevier, 2025-11-26) María Hormigos, Roberto; Monago Maraña, Olga; Zapardiel Palenzuela, Antonio; González Crevillén, Agustín; Universidad Nacional de Educación a Distancia (UNED)/Santander
    Ultraviolet A (UV-A) radiation from the Sun is a significant risk factor for skin cancer owing to long-term exposition for outdoor workers. The growing need for wearable health monitoring devices demands real-time UV-A sensors with high analytical performance to avoid skin conditions resulting from prolonged UV-A exposure. In this work, we aimed to develop a novel, power-less, low-cost, long-term-stable, and flexible wearable sensor. Such a sensor is based on basic bismuth nitrate (BBN) covered with graphene quantum dots (GQDs) as a photodetector. BBN@GQD photoelectrical material was produced by a very low-cost pyrolytic procedure in gram-scale quantities on a simple hot plate. GQDs improved photoelectrical activity of BBN, yielding good responsivity of 0.25 mA·W−1 (at 0 V bias, incident light intensity 17 μW·cm−2 and 365 nm wavelength). The combination of BBN@GQD and ITO electrodes provided a very sensitive and selective photodetector (a limit of detection of 1.6 ± 0.6 μW·cm−2 light intensity at 0 V bias for 365 nm UV-A wavelength), better than most current UV-A photodetectors. Its high sensitivity at 0 V bias enables its employment as a functional power-free real-time UV-A monitor device. Moreover, the wearable sensor showed acceptable reproducibility (18.9 % relative standard deviation at 12.5 μW·cm−2 light intensity) and long-term stability (up to 1 month of storage). This work proposes a promising wearable device for UV-A monitoring in an outdoor environment, using a new photosensitive material (BBN@GQD), which offers new opportunities in the development of UV photodetectors.
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    Acrylamide-fat correlation in californian-style black olives using near-infrared spectroscopy
    (MDPI, 2023-09-06) Montero Fernández, Ismael; Martín Tornero, Elísabet; Martín Vertedor, Daniel; Fernández Fernández, Antonio; Monago Maraña, Olga
    Californian-style is one of the most important black table olive elaborations. During its processing, table olives produce acrylamide, a potential carcinogen compound generated during sterilization. In the present study, total fat and acrylamide content in Californian-style table olives were determined and a regression between them was performed (acrylamide concentration range: below limit of detection—2500 ng g−1 and 8–22% for total fat). Nowadays, there are fast and efficient new techniques, such as Near-Infrared Spectroscopy (NIRS) to measure fat content parameters. In that sense, NIRS was used to perform a fat content quantification model in olives in order to indirectly determine acrylamide content. Calibration models for fat quantification were obtained in defatted olive pastes from a unique variety and for olive pastes from different varieties. In the first case, best results were obtained since only one variety was used (R2 = 0.9694; RMSECV = 1.31%; and REP = 8.4%). However, in the second case, results were still acceptable R2 = 0.678, RMSECV = 2.3%, REP = 17.7% and RMSEV = 2.17%. Regression coefficients showed the most influence variables corresponded with fat. The determination coefficient for the fat and acrylamide correlation was high (r = 0.877), being an efficient approach to find out the contribution of fat degradation to acrylamide synthesis in table olives.
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    Second-order calibration in combination with fluorescence fibre-optic data modelling as a novel approach for monitoring the maturation stage of plums
    (Elsevier, 2020-04-15) Domínguez Manzano, Jaime; Muñoz de la Peña, Arsenio; Durán Merás, Isabel; Muñoz de la Peña, Arsenio; Monago Maraña, Olga
    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.
  • Miniatura
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    Four- and five-way excitation-emission luminescence-based data acquisition and modeling for analytical applications. A review
    (Elsevier, 2019-11-20) Alcaraz, Mirta R.; Goicoechea, Héctor C.; Muñoz de la Peña, Arsenio; Monago Maraña, Olga
    The latest advances in both theory and experimental procedures on third-order/four-way and fourth-order/five-way calibration methods are discussed. This report is focused on excitation–emission (fluorescence and phosphorescence) matrices generation, employing different variables as the third data mode (time retention in chromatography, pH gradient, fluorescence/phosphorescence lifetime, kinetics, or other chemical treatments). Fully capitalizing on the second-order advantage, it has been possible to develop appealing analytical applications in spite of the complexity of the data. Extraction of the significant chemical information about the system under study as well as the individual abundance of the contributing constituents after proper higher-order data decomposition has allowed to analytical researchers performing quantitative analysis of complex samples. The experimental works reported up to the present are introduced and discussed in order to illustrate concepts. Throughout this work, the analytical benefits achieved by modeling third- and fourth-order data are exposed, attempting to contribute to the ongoing debate in the chemometric community regarding the existence and the true nature of the third-order advantage.
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    Analytical technique and chemometrics approaches in authenticating and identifying adulteration of paprika powder using fingerprints: a review.
    (Elsevier, 2022) Durán Merás, Isabel; Muñoz de la Peña, Arsenio; Galeano Díaz, Teresa; Monago Maraña, Olga
    Paprika powder authentication has gained interest in recent decades along with increases in its consumption. There are different Protected Designation of Origins (PDOs) around the world, some of them are from Spain, and it is important to assure the quality parameters that they offer and to provide a guaranty about their quality and authentication. This review covers the latest advances concerning the targeted and untargeted methodologies. These methodologies have been developed to ensure paprika powder authenticity, corroborating that it belongs or not to a certain PDO and that it complies with the regulations and legal standards for its consumption, as well as detection of possible adulterations, mainly with Sudan dyes, which are illegal colorants. Differences between spectroscopic and non-spectroscopic methods have been emphasized. As observed from the literature, paprika powder has not been extensively studied, but the number of papers has been increasing in recent years.
  • Miniatura
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    Evaluation of hydrophilic and lipophilic antioxidant capacity in Spanish tomato paste: usefulness of front-face total fluroescence signal combined with PARAFAC
    (Springer, 2021-12-01) Pardo Botello, Rosario; Chamizo Calero, Fátima; Rodríguez Corchado, Raquel; Torre Carreras, Rosa de la; Galeano Díaz, Teresa; Monago Maraña, Olga
    The hydrophilic and lipophilic antioxidant activities due to the main bioactive components present in Spanish tomato paste samples were studied, using standardized and fluorescent methods. After extraction, phenolic antioxidants (Folin-Ciocalteu method) and total antioxidant activity (TEAC assay) were evaluated, examining differences between hydrophilic and lipophilic extracts corresponding to different samples. Total fluorescence spectra of extracts (excitation-emission matrices, EEMs) were recorded in the front-face mode at two different ranges: 210-300 nm/ 310-390 nm, and 295-350 nm/380-480 nm, for excitation and emission, respectively, in the hydrophilic extracts. In the lipophilic extracts, the first range was 230-283 nm/290-340 nm, while the second range was 315-383 nm/390-500 nm for excitation and emission, respectively. EEMs from a set of 22 samples were analyzed by the second-order multivariate technique Parallel Factor Analysis (PARAFAC). Tentative assignation of the different components to the various fluorophores of tomato was tried, based on literature. Correlation between the antioxidant activity and score values retrieved for different components in PARAFAC model was obtained. The possibility of using EEMs-PARAFAC to evaluate antioxidant activity of hydrophilic and lipophilic compounds in these samples was examined, obtaining good results in accordance with the Folin-Ciocalteu and TEAC assays.
  • Miniatura
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    Untargeted authentication of fruit juices based on electrochemical fingerprints combined with chemometrics. Adulteration of orange juice as case of study
    (ELSEVIER, 2024) Monago Maraña, Olga; Zapardiel Palenzuela, Antonio; González Crevillén, Agustín
    This work presents a novel strategy for authentication of fruit juices. The methodology is based on an electrochemical method combined with chemometrics. In addition, the case of orange juice adulteration with grapefruit juices was studied using this methodology. The electrochemical fingerprint of different juices showed the influence from different polyphenols according to the type of fruit. First, Principal Component Analysis (PCA) was able to differentiate clusters of different juices, being the higher group distance within apple, orange, and grape juices samples. On the other hand, partial least-squares – discriminant analysis (PLS-DA) and PCA-linear discriminant analysis (LDA) were used as classification methods, obtaining better results for orange and apple models. Furthermore, good results were obtained for the authentication of orange juices, compared to other juices, with an error rate of 0.04 for cross-validation. In the case of adulteration of orange juice was detected using PLS-DA at an adulteration level as low as 1%. Regression vectors for all models highlighted identifiable potential values that could be related to the main polyphenols in each type of fruit. This electrochemical method is rapid, low-cost, and compatible with on-site analysis compared to other laborious analysis described in the literature.
  • Miniatura
    Publicación
    Raman spectroscopy as a tool for characterisation of quality parameters in Norwegian grown apples during ripening
    (ELSEVIER, 2024) Monago Maraña, Olga; Wold, Jens Petter; Remberg, Siv Fagertun; Sanden, Karen Wahlstrøm; Afseth, Nils Kristian
    This study shows for the first time the feasibility of Raman spectroscopy as a non-destructive method to follow the ripening process of apple fruits. Two different varieties of apples were studied: ‘Aroma’ and ‘Elstar’. By visual inspection, Raman spectra showed that the starch content was higher in ‘Elstar’ apples compared to ‘Aroma’. The degradation of starch over time could be detected in the Raman spectra, indicating that the method can be used to monitor the ripening process. The ripeness markers starch index, soluble solids content (SSC), and the sugars glucose, fructose and sucrose were determined with traditional destructive methods. Cross validated calibration models based on Raman spectroscopy were obtained for all quality parameters, and test set validation offered good results, with R2 in the range 0.4–0.86 for ‘Aroma’ and 0.4–0.95 for ‘Elstar’, respectively. The regression coefficients showed that the calibrations relied on Raman bands associated with starch and different sugars. The results suggest that Raman spectroscopy in the future could be used to determine the optimal time of harvesting and to sort apples into different degrees of ripeness.