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Fernández Hernando, Pilar

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  • Miniatura
    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 Mª
    This 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 L􀀀1 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 L􀀀1 and 0.8 and 0.98 g L􀀀1 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).
  • Miniatura
    Publicación
    Evaluation of total phenol pollution in water of San Martin Canal from Santiago del Estero, Argentina.
    (Elsevier, 2018-05) Acosta Rosales, Carina Andrea; López, Clara; Paniagua González, Gema; Garcinuño Martínez, Rosa Mª; Fernández Hernando, Pilar
    Santiago del Estero is a province located in northwestern Argentina. The Dulce River is used for irrigation through a vast network of channels and ditches, including the San Martin Canal (SMC), which crosses the capital city of Santiago del Estero. This canal's water is used for drinking, as well as recreational use for the general population. However, this river has been seriously polluted for several decades. The present study focuses on the identification and the quantification of the water pollution levels of total phenols in the SMC according to the seasonal periods. Water samples from various areas of the canal in different months of the year, extending from December to September, were collected for analysis. Additionally, the concentration of total dissolved solids (TDS), chlorides, sulphates, nitrites and organic matter, as well as water hardness and alkalinity, were analysed in order to conduct a more complete study of the contamination of this area. The results showed a worrying total phenol concentration that exceeded the limit set by Argentine legislation for drinking water, as well as water for recreational use (5 μg/L). The total phenol (TP) concentration was directly determined by a molecular absorption spectroscopy method based on a new flow injection analysis system (FIA). Under the selected experimental conditions, the detection and quantification limits were 0.0490 and 0.1633 μg/mL, respectively. The developed method provides a number of improvements related to the speed of analysis, the restricted consumption of the reagents and sample volumes and the unnecessary sample treatment that contribute to environmentally friendly analytical chemistry. The results showed that TP make a significant contribution in the SMC pollution, especially during the months of April (400 ± 110 μg/L) and September (240 ± 20 μg/L). A high sulphate concentration that was higher than the limit allowed by the legislation was also found.
  • Miniatura
    Publicación
    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 Mª
    The 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.
  • Miniatura
    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 Mª
    The 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.
  • Miniatura
    Publicación
    Synthesis and characterization of a molecularly imprinted polymer for the determination of spiramycin in sheep milk
    (Elsevier, 2017-04-15) Durand Alegría, Jesús Senén; García Mayor, M Asunción; Paniagua González, Gema; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa Mª
    A series of molecularly imprinted polymers (MIPs) comprising reactionary sites which are complementary to macrolide antibiotic spiramycin (SPI) were synthetized by noncovalent bulk polymerization technique. MIPs were synthesized under different polymerization process and their recognition efficiency was evaluated in binding studies in comparison with non-imprinted polymers. The best MIP was morphologically characterized and equilibrium assays were carried out. The MIP was evaluated as a sorbent for extraction and preconcentration of SPI from aqueous and sheep milk samples, and an off-line MISPE method followed by high-performance liquid chromatography with UV diode-array detection was established. Good linearity were obtained for SPI in a range of 24–965 μg kg−1 and the average recoveries at three spiked levels in milk samples were higher than 90% (RSD < 5%). Limit of quantification was 24.1 μg kg−1. Cross-reactivity studies from other macrolides with similar structure were tested. The optimum imprinted polymer showed a good selectivity and affinity for SPI, demonstrating the potential of the proposed MISPE for rapid, sensitive and effective sample pretreatment for selective determination of SPI in sheep milk samples.
  • Miniatura
    Publicación
    Assessing microplastic ingestion and occurrence of bisphenols and phthalates in bivalves, fish and holothurians from a Mediterranean marine protected area
    (Elsevier, 2022-08-07) Rios Fuster, Beatriz; Alomar, Carme; Deudero, Salud; Paniagua González, Gema; Soliz Rojas, Dulce Lucy; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa Mª
    Microplastic (MP) ingestion, along with accumulated plasticizers such as bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS), and phthalates represented by diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis (2-ethylhexyl) phthalate (DEHP), were quantified in bivalves, fish, and holothurians collected from a coastal pristine area at the western Mediterranean Sea. MP ingestion in sediment-feeders holothurians (mean value 12.67 ± 7.31 MPs/individual) was statistically higher than ingestion in bivalves and fish (mean 4.83 ± 5.35 and 3 ± 4.44 MPs/individual, respectively). The main ingested polymers were polyethylene, polypropylene, and polystyrene. The levels of BPS, BPF, and DEHP were highest in bivalves' soft tissue; BPA and DBP had the highest levels in the holothurians’ muscle. In addition, the levels of all plasticizers assessed were lowest in fish muscle; only BPA levels in fish were higher than in bivalves, with intermediate values between those of bivalves and holothurians. This study provides data on exposure to MPs and plasticizers of different species inhabiting Cabrera Marine Protected Area (MPA) and highlights the differences in MP ingestion and levels of plasticizers between species with different ecological characteristics and feeding strategies.
  • Miniatura
    Publicación
    Permanent oriented antibody immobilization for digoxin determination with a flow-through fluoroimmunosensor
    (Springer, 2003-02-28) Durand Alegría, Jesús Senén; Pérez Conde, Concepción; Fernández Hernando, Pilar; Paniagua González, Gema
    Digoxin is a very important compound in clinical chemistry and is indicated in the treatment of congestive heart failure and artery disease. The measurement of serum digoxin concentration is necessary owing to the narrow therapeutic range of this drug. Further, even with similar dosage regimens, the biological response of patients often results in very different concentrations of digoxin in serum. Concentrations of greater than 2.6 mmol/L are generally interpreted as toxic in adult patients. Most methods for digoxin determination are based on gas chromatography or radiochemical and enzymatic immunoassay techniques. However, some of these methods are tedious and difficult to automate. Nowadays, they are being replaced by more practical immunoassay techniques, involving, for example, fluorescent immunosensors that allow rapid, automated and selective digoxin determinations. This paper reports a new flow–through fluoroimmunosensor for digoxin determination, the function of which is based on antibodies immobilized on an inmunoreactor of controlled pore glass (CPG). The immunosensor has a detection limit of 1.20 μg/L and provides high reproducibility (RSD = 4.5% for a concentration of 0.0025 mg/L, and RSD = 6.7% for 0.01 mg/L). The optimum working concentration range was found to be 1.2×10-3 - 4.0×10-2 mg/L. The lifetime of the immunosensor was about 50 immunoassays, if stored unused its lifetime can be extended to three months. A sample speed of about 10–12 samples per hour can be attained. Possible interference from substances with structures similar to digoxin (morphine, heroine, tebaine, codeine, pentazocine and narcotine) was investigated. No cross-reactivity was seen at the highest digoxin:interferent ratio studied (1:100). The proposed fluoroimmunosensor was successfully used to determine digoxin concentrations in human serum samples.
  • Miniatura
    Publicación
    A MIP-based flow-through fluoroimmunosensor as an alternative to immunosensors for the determination of digoxin serum samples
    (Springer, 2009-01-09) Durand Alegría, Jesús Senén; Paniagua González, Gema; Fernández Hernando, Pilar
    This work reports a comparative study of two automated flow-through fluorosensors for the determination of digoxin in serum samples: an immunosensor with an anti-digoxin polyclonal antibody as the reactive phase permanently immobilized on CPG, and a sensor with a selective reaction system based on a methacrylic molecularly imprinted polymer (MIP) synthesized by bulk polymerisation. The variables affecting the sensitivity and dynamic range of the sensors (e.g., the carrier and elution solutions, flow-rates, pH and reagent concentrations) were optimised and the binding characteristics of their reactive phases compared in a competitive fluorescent assay. Digoxin was reproducibly determined by both sensors at the mg L-1 level (detection limit= 1.20×10-3 mg L-1 and RSD= 4-7% for the immunosensor; detection limit= 1.7×10-5 mg L-1 and RSD= 1-2% for the MIP sensor). No cross reactivity with digoxinrelated compounds was seen for either sensor at a digoxin:interferent ratio of 1:100. The lifetime of the immunosensor was about 50 immunoassays; its shelf life, when unused, is about three months. The lifetime of the MIP sensor was over 18 months. Both sensors were used to determine the digoxin concentration of human serum samples with satisfactory results.
  • Miniatura
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    Assessment of the impact of aquaculture facilities on transplanted mussels (Mytilus galloprovincialis): Integrating plasticizers and physiological analyses as a biomonitoring strategy
    (Elsevier, 2022-02-15) Rios Fuster, Beatriz; Alomar, Carme; Capó Fiol, Xavier; Silva, Mónica; Solé, Montserrat; Freitas, Rosa; Deudero, Salud; Paniagua González, Gema; Soliz Rojas, Dulce Lucy; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa Mª; https://orcid.org/0000-0002-3499-5494
    The growing plastic production and its continuous use is a significant problem. In addition, aquaculture practices have experienced a considerable growth and plastic is widely used in these activities, hence plasticizers must be considered due to their potential ecotoxicological impacts on species. Mussels placed inside an Integrated Multi-Trophic Aquaculture (IMTA) system and at two control locations were employed to quantify the ingestion of anthropogenic particles and associated chemical plasticizers, such as bisphenol A (BPA) jointly to bisphenol F (BPF) and bisphenol S (BPS), and phthalates represented by diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). In addition, some metabolism and oxidative stress related parameters were measured in mussels’ whole soft tissue. Anthropogenic particle ingestion of mussels increased over time at the three locations and the following order of abundance of pollutants was observed: BPA> BPF> DEHP> DBP> BPS> DEP. Even though no differences according to location were found for pollutants’ occurrence, time trends were evidenced for BPA and DEHP. On the other hand, a location effect was observed for biomarkers with highest values detected in mussels located at the vicinities of the aquaculture facility. In addition, a reduced detoxification activity was observed over time parallel to BPA decrease.
  • Miniatura
    Publicación
    A morphological study of molecularly imprinted polymers using the scanning electron microscope
    (Elsevier, 2006-01) Durand Alegría, Jesús Senén; Paniagua González, Gema; Fernández Hernando, Pilar
    Molecular imprinting is an emerging technique for producing polymers with applications in affinity-based separation, in biomimetic sensors, in catalysis, etc. This variety of uses relies upon the production of polymers with different affinities, specificities, sensitivities and loading capacities. Research into the development of molecular imprinted polymers (MIPs) with new or improved morphologies – which involves modification of the polymerisation process – is therefore underway. This paper reports a comparative study of non-covalent MIPs synthesised by “bulk” polymerisation using digoxin as template. These were synthesised under different conditions, i.e., changing the functional monomers employed (methacrylic acid or 2-vinylpyridine), the porogens (acetonitrile or dichloromethane) used, and by altering the volume of the latter. The polymerisation process was allowed to proceed either under UV light or in a thermostat-controlled waterbath. The surface morphology (was determined by scanning electron microscopy) and the ability of the different polymers to selectively rebind the template was then evaluated.