Column classification and selection for the determination of antibiotics by micellar liquid chromatography

Seven commercially available: Zorbax C18, Kromasil C18, C8, cyano, phenyl, monolithic and amino stationary phases columns, have been characterized and classified into broadly similar types to simplify column choice. The results were evaluated employing cluster analysis, which shows several interesting groups based on distances (Minkowski and Euclidean) in agreement with the manufacturer’s claims: chain density of the stationary phase used, and the presence or not a silica base. Finally, results showed that C18 columns offer the best chromatographic characteristics for separation and quantification of antibiotics in micellar liquid chromatography

Simultaneous separation and determination of quinolones in pharmaceuticals by micellar liquid chromatography

A rapid and simple liquid chromatographic procedure using micellar mobile phases is reported for the separation and determination of four quinolones (pipemidic acid, levofloxacin, norfloxacin and moxifloxacin) in pharmaceuticals. This purpose was achieved without any previous pretreatment step in a C18 column using a micellar mobile phase of 0.15 M sodium dodecyl sulphate, 2.5% propanol and 0.5% triethylamine at pH 3, with retention times below 12 min. For detection, the diode-array UV-Vis set at 276 nm was used. The limits of detection and quantification were between 8-51 and 28-171 ng/mL, respectively. This method was validated in terms of intra-day and inter-day precision and accuracy, and robustness. Calibration curves over the concentration range of 0.1-50 μg/mL were linear (r2 > 0.9997) and. Good claim percentages (96–106 %) were obtained in the analysis of pharmaceutical formulations. The results show that the procedure is suitable for the routine analysis of drugs

Novel strategy for the revalorization of olive (Olea europaea) residues based on the extraction of bioactive peptides

This work proposes a new strategy for the revalorization of residual materials from table-olive and olive oil production based on the extraction of bioactive peptides. Enzymatic hydrolysates of olive seed protein isolate were prepared by treatment with five different proteases: Alcalase, Thermolysin, Neutrase, Flavourzyme and PTN. Although all hydrolysates presented antioxidant properties, Alcalase was the enzyme that yielded the hydrolysate with the highest antioxidant capacity. All hydrolysates showed antihypertensive capacity, obtaining IC50 values from 29 to 350 mu g/ml. Thermolysin was the enzyme which yielded the hydrolysate with the highest ACE-inhibitory capacity. Hydrolysates were fractionated by ultrafiltration showing a high concentration of short chain peptides, which exhibited significantly higher antioxidant and antihypertensive capacities than fractions with higher molecular weights. Peptides in most active fractions were identified by LC-MS/MS, observing homologies with other recognized antioxidant and antihypertensive peptides. Finally, their antioxidant and antihypertensive capacities were evaluated after in vitro gastrointestinal digestion. (C) 2014 Elsevier Ltd. All rights reserved

PALEOBIODIVERSIDAD Y PALEOAMBIENTE DE FORMACIÓN DEL YACIMIENTO DE VALLIPÓN (FORMACIÓN ARTOLES)

En este trabajo se ha estudiado la paleobiodiversidad del yacimiento de Vallipón (Teruel). Para realizarlo se ha triado una muestra representativa del yacimiento (7 Kg) cebtrándose principalmente en los microvertebrados. Con los resultados obtenidos del triado y la bibliografía publicada del yacimiento se ha inferido su ambiente de formación.<br /

El uso del blog y el debate en el aprendizaje del medio ambiente

El presente Trabajo de Fin de Máster tiene como eje principal las actividades desempeñadas realizadas en el Prácticum II en el IES Ramón Pignatelli. La temática a tratar ha sido la ecología y el medio ambiente, dentro de la asignatura Biología y Geología de 4º de la ESO, y su diseño se basó en el currículo de Educación Secundaria Obligatoria recogido en la Orden ECD/489/2016, de 26 de mayo (vigente en el momento de realización del Prácticum).Esta memoria se adhiere a la modalidad A ofertada por la titulación. Consiste en el desarrollo de tres grandes bloques de contenido bien diferenciados: un primer bloque que consta de una introducción al trabajo y una presentación personal; un segundo bloque consistente en el análisis de dos actividades realizadas en las asignaturas cursadas durante el Máster; un tercer bloque donde se realiza la exposición y el análisis de la actividad docente impartida por la autora durante el Prácticum II. Cada uno de los tres bloques se han desarrollado de manera independiente y en el orden establecido.<br /

Monitoring of HAART regime antiretrovirals in serum of acquired immunodeficiency syndrome patients by micellar liquid chromatography

A methodology based on micellar liquid chromatography to monitor five antiretroviral drugs (lamivudine, stavudine, tenofovir, zidovudine and efavirenz) was proposed. Antiretrovirals were studied in sets of three, corresponding to each highly active antiretroviral therapy (HAART) regime, prescribed to acquired immunodeficiency syndrome (AIDS)-infected patients. Four aqueous micellar mobile phases buffered at pH 7 were optimized to separate these compounds, using sodium dodecyl sulfate as the tensioactive, and 1-propanol or 1-pentanol as the organic modifier. The composition of each mobile phase was optimized for each antiretroviral. The common separation conditions were: C18 apolar column (125 4.6 mm, 5 mm particle size), UV detection set at 214 nm, and mobile phase running at 1 mL min␣1 without controlling the temperature. The finally suggested method was validated for five analysed antiretroviral drugs following the US Food and Drug Administration guidelines in terms of: linearity between 0.5 and 50 ppm (r2 > 0.9995), sensitivity (LOD lower than 0.25 ppm), intra- and inter-day precision (<7.1 and <5.2%, respectively) and accuracy (recovery 88.5– 105.3% and 93.5–101.3%, respectively), as well as robustness (<6.5%). The proposed method was used to monitor the level of antiretrovirals in the serum of AIDS patients. The suggested methodology was found to be useful in the routine analysis of antiretrovirals in serum samples

Aproximación paleohistológica de los dinosaurios ornitópodos de la Formación Blesa (Barremiense, Teruel)

Este trabajo consiste en una aproximación paleohistológica de restos de ornitópodos pequeños y medianos procedentes del yacimiento de La Cantalera (Josa, Teruel) de edad barremiense inferior (Cretácico inferior).La aproximación paleohistológica se ha realizado mediante el estudio de diez láminas delgadas en microscopio petrográfico y análisis de tres ellas mediante FESEM. Las láminas delgadas se han realizado en secciones transversales y longitudinales de distintos restos óseos de ornitópodos.Los datos realizados mediante microscopio petrográfico han consistido en describir las láminas delgadas indicando los diferentes tipos de tejidos óseos observados, así como los minerales que se han podido identificar. El microscopio electrónico ha consistido en realizar análisis composicionales de tres de las muestra estudiadas. Los resultados indican que los restos fósiles de ornitópodos de La Cantalera pertenecían a individuos de edades variadas, dominando las etapas ontogenéticas juveniles. Los análisis realizados en FESEM indican que la diagénesis de los restos óseos ha sufrido varias etapas distinguibles por las relaciones texturales de los minerales.<br /

Use of micellar mobile phases for the chromatographic determination of melamine in dietetic supplements

Melamine is a nitrogen-rich industrial chemical which is occasionally used to increase the apparent protein content of different products destined for human and animal consumption. In this work, a liquid chromatographic procedure that uses micellar mobile phases of sodium dodecyl sulfate (SDS) buffered at pH 3, a C18 column and UV detection is reported for the determination of melamine in dietetic supplements. Samples were reconstituted with a SDS solution and were directly injected, thus avoiding long extraction and experimental procedures. Melamine was eluted in less than 10 min with no interference by other compounds of the matrices. The optimum mobile phase composition was taken by a chemometrical approach that considers the retention factor, efficiency and peak shape. Validation was performed following the indications of the European Commission (Decision 2002/657/EC). The following parameters were considered: linearity (0.02-100 μg mL(-1); R(2) = 0.9996), intra- and inter-day precisions (<12.4%), accuracy (90.0-101.3%), and robustness (less than 9.8% and 5.1%, for retention time and peak area, respectively). The limits of detection and quantification were 9 and 20 ng mL(-1), respectively. Recoveries for several spiked samples were in the 85.8-114.3% range. These results indicate that the proposed methodology is useful for routine analysis of control quality of infant formula and adult dietetic supplement

Application of a liquid chromatographic procedure for the analysis of penicillin antibiotics in biological fluids and pharmaceutical formulations using sodium dodecyl sulphate/propanol mobile phases a.

A direct injection liquid chromatography procedure was developed for the simultaneous determination of four penicillin antibiotics (amoxicillin, ampicillin, cloxacillin and dicloxacillin) in pharmaceutical formulations and physiological fluids (urine) using hybrid micellar mobile phases. These antimicrobials are used to treat gastrointestinal and systemic infections. The four penicillins were analysed using a Zorbax C18 reversed-phase column and detected at 210 nm. These antibiotics were separated by an interpretive optimisation procedure based on the accurate description of the retention and shape of the chromatographic peaks. Antibiotics were eluted in less than 16 min with no interference by the urine protein band or endogenous compounds using the mobile phase 0.11 M sodium dodecyl sulphate–6% propanol–0.01 M NaH2PO4 buffered at pH 3. The method was validated according to the Food and Drug Administration guideline, including analytical parameters such as linearity (R2 > 0.993), intra- and inter-day precisions (RSD, %: 0.1–4.4 and 1.2–5.9, respectively), and robustness for the four compounds. This method is sensitive enough for the routine analysis of penicillins at therapeutic urine levels, with limits of detection in the 1.5–15 ng mL−1 range and limits of quantification of 50 ng mL−1. Recoveries in a micellar medium and a spiked urine matrix were in the 92.4–108.2% and 96–110% ranges, respectively. Finally, the method was successfully applied to determine these antibiotics in urine samples and pharmaceutical formulations