Persona: Bravo Yagüe, Juan Carlos
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Bravo Yagüe
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Juan Carlos
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Publicación On-line flow injection molecularly imprinted solid phase extraction for the preconcentration and determination of 1-hydroxypyrene in urine samples(Elsevier, 2017-05-01) Serrano, Montserrat; Bartolomé, Mónica; Gañán Aceituno, Judith; Gallego Picó, Alejandrina; Bravo Yagüe, Juan Carlos; Paniagua González, Gema; Garcinuño Martínez, Rosa MªNew analytical strategies tend to automation of sample pre-treatment and flow analysis techniques provided a number of enhanced analytical methods allowing high throughput. Flow techniques are usually faster, more robust and more flexible than their batch equivalents. In addition, flow methods use less sample and reagent amounts and reduce analytical costs and waste. A flow injection solid-phase extraction pre-concentration system using a molecularly imprinted polymer (MIP) packed micro-column was developed for the determination of 1-hydroxypyrene in human urine with fluorescence detection. The pre-concentration of 1-hydroxypyrene on the MIP was carried out based on the specific retention of analyte by on-line introducing the sample into the micro-column system. Methanol and dichloromethane mixture was used to elute the retained analyte for fluorometric analysis. Important influencing factors were studied in detail, in batch and in flow (MISPE procedure optimisation, sample and eluent volumes, flow rate, dimensions of MIP micro-column and amounts of packing material, etc). To the best of our knowledge, this is the first on-line flow injection molecularly imprinted solid phase extraction for the pre-concentration and determination of hydroxylate PAH metabolite in urine samples. The optimised method was successfully applied to the determination of 1-Hydroxypyrene in spiked urine samples, with recoveries in the range of 74–85% and RSD<4.6%. Under optimum experimental conditions, the linearity concentration range used was 10–400 μg L−1, R2>0.996. We obtained limit of detection and quantification of 3.1 μg L−1 and 10.5 μg L−1, respectivelyPublicación Analysis of total arsenic content in purchased rice from Ecuador(Czech Academy of Agricultural Sciences, 2019-12-31) Atiaga Franco, Oliva L.; Otero, Xose L.; Gallego Picó, Alejandrina; Escobar Castañeda, Luis A.; Carrera Villacrés, David; Bravo Yagüe, Juan CarlosNatural and anthropogenic sources contribute to arsenic contamination in water and human food chain in Andean countries. Human exposure to arsenic via rice consumption is of great concern in countries where this crop is the dominant staple food, and limited information is available on the arsenic contamination on rice in Ecuador. This work was to contribute to the lack of knowledge analysing total arsenic by hydride generation-atomic absorption spectrometry in the samples of white, brown and parboiled rice purchased in Ecuadorian markets and produced in the two main rice wetlands in Ecuador, Guayas and Los Ríos, were carried out. For the samples from Guayas, arsenic concentration in white, brown and parboiled rice were 0.174 ± 0.014, 0.232 ± 0.021, and 0.186 ± 0.017 mg/kg respectively, whereas samples of white rice from Los Ríos showed a total arsenic level of 0.258 ± 0.037 mg/kg. This last arsenic concentration exceeds recommended maximum permissible limit by the FAO/WHO. Obtained data have available to estimate the Ecuadorian dietary exposure revealing serious health risk for populationPublicación Thermoluminescence and ATR-FTIR study of UVC-irradiated low-density polyethylene (LDPE) food packaging(Elsevier, 2024-12) Boronat Castaño, Cecilia; Correcher, Virgilio; Benavente Cuevas, José Francisco; Bravo Yagüe, Juan CarlosThis research aims to study the effects of ultraviolet C (UVC) radiation on low-density polyethylene (LDPE) food packaging. Main objectives include evaluating LDPE degradation and detecting UVC radiation using thermoluminescent dosimeters (TLDs) placed under LDPE samples. Results confirm accurate UVC detection after one hour of exposure, providing a useful tool for optimize food treatment procedures. ATR-FTIR spectroscopy analysis revealed subtle alterations (<8 % transmittance relative) in UVC-irradiated LDPE samples, including possible Csingle bondH breakage (2910 and 2848 cm−1) and potential single bondCdouble bondCsingle bond bond vibrations (1470 cm−1), among others. However, observed variations may stem from LDPE properties rather than entirely from UVC radiation. A comparative study of UVC-induced thermoluminescence (TL) emissions provided insights into various TLDs materials. TL kinetic analysis, using computerised glow curve deconvolution (CGCD) method, unveiled trap charge activation due to UVC exposure, including partial ionization, bleaching effect and photo-transfer (PTTL) processes. LDPE samples amplified UVC-TL responses, revealing intensity differences between the TLDs attributed to the PTTL process, accentuated by the lack of an annealing treatment. Additionally, chemical composition of the TL detectors such as, type, concentration, number, oxidation states and ionic radii of their dopants may influence UVC-TL response. Consequently, TL intensity ratios follow as: GR-200 (LiF: Mg, Cu, P) > TLD-100 (LiF: Ti, Mg) > TLD-400 (CaF2: Mn) > TLD-200 (CaF2: Dy). Thus, GR-200 detects ionizing radiation but cannot distinguish between ionizing and non-ionizing UVC radiation, while TLD-100 has limited effectiveness as a UVC radiation detector. In contrast, TLD-400 is suitable for detecting UVC radiation and TLD-200 emerges as the most favorable UVC detector, showing consistent response levels and minimal PTTL effect placed under the LDPE samples without the need of a thermal annealing treatment that makes the TLD-200 to be reusable in a low-cost measurement protocol.Publicación Selective extraction of diazepam and its metabolites from urine samples by a molecularly imprinted solid phase extraction (MISPE) method(MDPI, 2024-02) Gil Tejedor, Ana María; Bravo Yagüe, Juan Carlos; Paniagua González, Gema; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa MªIn this research, a molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using oxazepam (OZ) as a template molecule and was subsequently applied as a selective sorbent for the extraction of diazepam (DZP) and its metabolites in urine samples using an SPE cartridge. OZ, temazepam (TZ), nordiazepam (NZ) and DZP were analyzed in the final extracts by high-performance liquid chromatography with diode array detection (HPLC-DAD). The SPE extraction steps were optimized, and the evaluation of an imprinting factor was carried out. The selectivity of the method for OZ versus structurally related benzodiazepines (BZDs), such as bromazepam (BRZ), tetrazepam (TTZ) and halazepam (HZ), was investigated. Under the optimum conditions, the proposed methodology provided good linearity in the range of 10–1500 ng/mL, with limit of detection values between 13.5 and 21.1 ng/mL and recovery levels for DZP and its metabolites from 89.0 to 93.9% (RSD ≤ 8%) at a concentration level of 1000 ng/mL. The proposed method exhibited good selectivity, precision and accuracy and was applied to the analysis of urine samples from a real case of DZP intake.Publicación Enhancement of a Simple, Economic and Eco-Friendly Analytical Approach for the Extraction and Determination of Endocrine Disruptors from Plastics in Shrimp(MDPI, 2024-07-12) Soliz Rojas, Dulce Lucy; García González, Jorge; Paniagua González, Gema; Garcinuño Martínez, Rosa Mª; Bravo Yagüe, Juan Carlos; Fernández Hernando, PilarThe economic significance of the shrimp industry relies heavily on the comprehensive utilization of all of the shrimp’s parts. However, this importance is often threatened by common challenges such as disease and pollution, caused by prominent contaminants that are capable of exerting adverse effects either directly as physical pollutants or indirectly through the incorporation of additives or adsorbed chemicals. Among these substances are endocrine disruptors, which pose risks to both wildlife and human populations. In this study, 11 endocrine-disrupting compounds were determined (3 bisphenols, 3 phthalates, 3 pesticides, and 2 nonylphenols) through the development of a cost-effective, greener and cost-friendly method based on solid-phase matrix dispersion (MSPD) with high-performance liquid chromatography coupled with diode array detection (HPLC-DAD). Determinations were performed on different parts of the shrimp: the cephalothorax, abdomen, intestine and shell. Several variables were optimized in the extraction, separation and detection phases, resulting in average recoveries of about 90%. The limit of detection (LOD) varies depending on the analyte and matrix. At concentrations of 1 mg/kg in the cephalothorax+shells and 1.25 mg/kg in the abdomen+intestine, all compounds were detected, except for nonylphenols. The developed method has allowed the simultaneous determination of 11 endocrine disruptors in different parts of the shrimp samples. Furthermore, the MSPD has been demonstrated to be an efficacious, selective, and streamlined sample extraction method, eliminating the necessity for pretreatment steps such as centrifugation and filtration, as well as the use of large volumes of solvents.Publicación Identification and morphological characterization of different types of plastic microparticles(Elsevier, 2024-05-15) Soliz Rojas, Dulce Lucy; Paniagua González, Gema; Muñoz Arnanz, Juan; Bravo Yagüe, Juan Carlos; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa MªThe knowledge of the polymeric composition of microplastics (MPs) is interesting because offers useful information on the resistance, durability, and degradability of these materials, also allowing progress in the control of this contamination. However, there is currently a lack of reliable standardized methods for the identification, and characterization of the plastic microparticles. This work uses different techniques in a complementary manner for the identification, and characterization of MPs that more frequently are found in the environment. A total of 10 types of plastics were collected (polystyrene (PS), polyethylene terephthalate (PETE), polyethylene (PE), high- and low-density polyethylene (HDPE and LDPE, respectively), polyvinyl chloride (PVC), polypropylene (PP), polytetrafluoroethylene (PTFE), Polyamide (PA, Nylon 6,6) and poly-carbonate (PC)) and their chemical identification were analyzed by reflectance-attenuated infrared (FTIR-ATR). Furthermore, the samples were observed using light microscopy, and scan-ning electron microscopy (SEM). Also, staining with 12 different dyes was performed to improve the identification of microplastics. The results of this study revealed that PETE, PE, HDPE and LDPE, whose SEM images exhibited smoothness and flat uniformity of their surface, were not (or less) susceptible to adsorb staining solutions while PP, PA, PVC, and PTFE, were capable of adsorbing the dye solutions.Publicación Comparing the effect of electron beam, beta and ultraviolet C exposure on the luminescence emission of commercial dosimeters(Elsevier, 2023-07-05) Correcher, Virgilio; Sarasola Martín, Iciar; García Guinea, Javier; Benavente Cuevas, José Francisco; Boronat Castaño, Cecilia; Bravo Yagüe, Juan CarlosThis paper reports on the luminescence characterization of TLD-100 (LiF: Ti, Mg), TLD-200 (CaF2: Dy), TLD-400 (CaF2: Mn) and GR-200 (LiF: Mg, Cu, P) dosimeters exposed to electro beam, beta and ultraviolet C radiation -UVC-. All of them show high sensitivity to radiation regardless of whether it is ionizing or partially ionizing radiation based on their luminescence properties (cathodoluminescence -CL- or thermoluminescence -TL-). CL emission differs significantly among them in shape and intensity due to their chemical compositions. LiF samples display three maxima at: (i) 300-450 nm linked to intrinsic and structural defects, (ii) a green waveband probably due to F3+ centres or the presence of hydroxyl groups and (iii) the red-infrared emission band associated with F2 centres. However, CL spectra from the CaF2 dosimeters display meaningful differences due to the dopant. TLD-200 is characterized by an emission with four sharp individual peaks in the green-IR spectral region (due to the Dy3+), whilst TLD-400 exhibits a broad maximum peaked at ̴ 500 nm (linked to the Mn2+). On the other hand, the variation in the TL glow curves allows to discriminate the TLDs exposed to beta and UVC radiation since they give rise to different chemicalphysical processes and that have been studied from the estimation of the kinetic parameters by means of the Computerised Glow Curve Deconvolution (CGCD) method.Publicación Ultraviolet C radiation on polypropylene: A potential way to reduce plastic pollution(Elsevier, 2024) Correcher, Virgilio; Boronat Castaño, Cecilia; Garcia Guinea, Javier; Bravo Yagüe; Bravo Yagüe, Juan Carlos; https://orcid.org/0000-0003-0864-6861; https://orcid.org/0000-0003-1848-3138This study investigates the application of ultraviolet C (UVC) radiation to extend the lifetime of healthcare items containing polypropylene (PP), particularly personal protective equipment (PPE). The main objectives involve assessing possible PP damage from UVC exposure and detecting UVC treatment within PP samples. FTIR spectroscopy and Raman spectroscopy reveal slight degradation in UVC-irradiated PP samples, demonstrating resilience post-treatment. Investigations using commercial thermoluminescence dosimeters (TLD-100, TLD-200, TLD-400 and GR-200) positioned under varying thicknesses of PP (0.20 and 0.80 mm) identify TLD-100 as a promising UVC detector. Conversely, TLD-200 and TLD-400 do not prove to be effective detectors, exhibiting similar behavior to the dosimeters without a plastic sample. And GR-200 does not possess the capability to differentiate between ionizing and non-ionizing components of UVC radiation. This research emphasizes the role of UVC to prolong the lifetime of healthcare items containing PP, thus aiding in efforts to reduce plastic pollutionPublicación Methacrylic acid-ethylene glycol dimethacrylate polymeric sorbent for the removal of estrogens from water(['Estrogens', 'Removal', 'Polymer', 'Sorbent', 'Waters', 'Balaban Publishers – Desalination Publications'], 2018-11) Gallego, Alejandrina; Bravo Yagüe, Juan Carlos; Paniagua González, Gema; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa MªThe presence of estrogens in environmental waters can cause adverse effects to aquatic organisms. In the last years, diverse researches have been focussed on the development of cost-effective methods for the removal of these compounds in water. In this paper, a series of methacrylic acid-ethylene glycol dimethacrylate polymers with different monomers ratio were synthesised by photochemical (UV irradiation at 365 nm) or thermal (oven at 60°C) initiation. Batch and continuous flow experiments were carried out to evaluate the capacity of these polymers to adsorb estradiol (E2), ethinylestradiol (EE2) and dienestrol (DEN). Adsorption isotherm studies revealed that Langmuir isotherm model was fitted with a better correlation than Freundlich isotherm. Finally, continuous flow experiments were carried out by microcolumn studies to check the suitability of the polymeric sorbent for the removal of estrogens from real water samples. When continuous removal experiments at 8 mL min–1 flow rate were carried out, breakthrough adsorption capacities of 28.5, 38 and 69.7 mg g–1 for E2, EE2 and DEN, respectively, were achieved.Publicación Assessment of molecularly imprinted polymers as selective solid-phase extraction sorbents for the detection of cloxacillin in drinking and river water(MDPI, 2023-11-03) Collado, Eduardo José; Paniagua González, Gema; Bravo Yagüe, Juan Carlos; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa MªThis paper describes a new methodology for carrying out quantitative extraction of cloxacillin from drinking and river water samples using a molecularly imprinted polymer (MIP) as a selective sorbent for solid-phase extraction (MISPE). Several polymers were synthesized via thermal polymerization using cloxacillin as a template, methacrylic acid (MAA) as a functional monomer, ethyleneglycoldimethacrylate (EGDMA) as a cross-linker and different solvents as porogens. Binding characteristics of the adequate molecularly imprinted and non-imprinted (NIP) polymers were evaluated via batch adsorption assays following the Langmuir and Freundlich isotherms and Scatchard assays. The parameters related to the extraction approach were studied to select the most appropriate polymer for cloxacillin determination. Using the optimized MIP as the SPE sorbent, a simple sample treatment methodology was combined with high-performance liquid chromatography (HPLC) to analyze cloxacillin residues in drinking and river water. Under the optimum experimental conditions, the MISPE methodology was validated using spiked samples. The linearity for cloxacillin was assessed within the limits of 0.05–1.5 g L1 and the recovery percentage was higher than 98% (RSD < 4%). The limits of detection and limits of quantification were 0.29 and 0.37 g L1 and 0.8 and 0.98 g L1 for drinking and river water, respectively. The selectivity of MIP against other ß-lactam antibiotics with similar structures (oxacillin, cefazoline, amoxicillin and penicillin V) was studied, obtaining a good recovery higher than 85% for all except cefazoline. The proposed MISPE-HPLC methodology was successfully applied for the detection of cloxacillin in drinking water from Canal de Isabel II (Madrid) and river water from the Manzanares River (Madrid).