Persona: Fernández Hernando, Pilar
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Publicación Molecularly imprinted SPE and MEKC with in-capillary sample preconcentration for the determination of digoxin in human urine.(Wiley, 2012-06) Guijarro Díez, Miguel; Crego, Antonio Luis; Marina Alegre, María Luisa; Paniagua González, Gema::virtual::2777::600; Fernández Hernando, Pilar::virtual::2778::600; Paniagua González, Gema; Fernández Hernando, Pilar; Paniagua González, Gema; Fernández Hernando, Pilar; Paniagua González, Gema; Fernández Hernando, PilarMolecularly imprinted solid-phase extraction (MISPE) combined with MEKC was used for clean-up, preconcentration and determination of digoxin in the presence of its aglycon digoxin (digoxigenin) in human urine samples. In addition, the use of an in-capillary sample concentration electrophoretic technique by sweeping was investigated to enhance the concentration sensitivity in MEKC. The highly selective, fast and effective sample pretreatment by MISPE along with the preconcentration by sweeping could overcome the low sensitivity of the highly efficient capillary electrophoresis separation with UV detection. The optimization of the variables affecting the separation as well as MISPE conditions procedure was carried out to select the best conditions of selectivity and sensitivity to determine digoxin at low concentration levels in urine. To demonstrate the suitability of the developed method several analytical characteristics (selectivity, linearity, accuracy, precision, and LOD) were evaluated. Satisfactory results were obtained in terms of linearity (r > 0.99), recovery (95.4–96.5% with RSD from 1.3% to 2.6%), precision (RSD from 0.3% to 1.7% for migration times and from 2.1% to 7.3% for corrected peak areas), and sensitivity (LODs of 6 μg/L with 5 mL of sample or 1.2 μg/L with 25 mL). The proposed MISPE-MEKC method was satisfactorily applied to the analysis of spiked human urine samples achieving a concentration factor up to 7500-fold.Publicación Synthesis and characterization of a molecularly imprinted polymer for the determination of spiramycin in sheep milk(Elsevier, 2017-04-15) Durand Alegría, J.S.; García Mayor, M Asunción; Paniagua González, Gema; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa MªA 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.Publicación Occurrence of erythromycin residues in sheep milk. Validation of an analytical method(Elsevier, 2015-04) Soledad Rodríguez, Beatriz Elena; Durand Alegría, Jesús Senén; García Mayor, M Asunción::virtual::2783::600; Paniagua González, Gema::virtual::2784::600; Fernández Hernando, Pilar::virtual::2785::600; Garcinuño Martínez, Rosa Mª::virtual::6721::600; García Mayor, M Asunción; Paniagua González, Gema; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa Mª; García Mayor, M Asunción; Paniagua González, Gema; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa Mª; García Mayor, M Asunción; Paniagua González, Gema; Fernández Hernando, Pilar; Garcinuño Martínez, Rosa MªThe paper describes a new and selective analytical sample treatment for quantitative extraction and preconcentration of erythromycin in presence of other macrolide antibiotics in sheep milk samples. The methodology is based on the use of a molecular imprinted polymer (MIP) employed as solid phase extraction sorbent (MISPE). The synthesized material by bulk polymerization using erythromycin (ERY) as template was evaluated as solid phase extraction sorbent, in a novel sample treatment technique that can be coupled to high-performance liquid chromatography with diode-array detector (HPLC-DAD). MIP selectivity was studied for other macrolide antibiotics with similar structures, such as tylosin (TYL), spiramycin (SPI), josamycin (JOS), roxithromycin (ROX) and ivermectin (IVER) getting recoveries for these interferents lower than 35%, for all cases except for ROX, which recoveries were around 85%. The variables affecting the molecularly imprinted solid-phase extraction (MISPE) procedure were optimized to select the best conditions of selectivity and sensitivity to determine ERY at concentration levels established by EU legislation in sheep milk. Under the selected experimental conditions, quantification limit was 24.1 µg kg−1. Recoveries were higher than 98%, with RSDs between 0.7% and 2%. The proposed MISPE-HPLC method was validated and successfully applied to ERY analysis in sheep milk samples.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 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 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, PilarSantiago 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.