Micellar liquid cromatography in bioanalytical chemistry

En la cromatografia líquida micel·lar (MLC), la fase mòbil és composta per un surfactant i un alcohol. Els paràmetres que s'han d'optimitzar en la MLC són el tipus de columna, el pH, la naturalesa del surfactant i el modificador, i les seves concentracions. L'optimització es realitza utilitzant una estratègia interpretativa en la qual la millor fase mòbil se selecciona per a estudis de validació. Els mètodes optimitzats en MLC proporcionen separacions ràpides, eficaces, i permeten la determinació d'una gran varietat de substàncies en una matriu complexa. La MLC és una tècnica útil per a identificar medicaments en fluids biològics, que sovint es poden injectar directament al sistema cromatogràfic fins i tot en presència d'uns altres composts, incloent- hi proteïnes, sense cap altre pretractament que la filtració. En descriure les moltes aplicacions de la MLC, aquesta revisió inclou exemples agafats de la literatura, i també resultats recents de la mateixa recerca dels autors. Descriu l'aproximació teòrica, l'estratègia d'optimització i les aplicacions de la MLC en la determinació de grups diferents de substàncies de medicaments. Els compostos i les matrius en discussió són els següents: antidepressius en farmacèutics, agents de blocatge de canal de calci en sèrum, anserina i carnosina en mostres de carns, tiramina i triptamina en vins, i sulfonamides en llet.In micellar liquid chromatography (MLC), the mobile phase is composed of a surfactant and an alcohol. The parameters that must be optimized in MLC are the type of column, the pH, the nature of the surfactant and modifier, and their concentrations. Optimization is performed using an interpretive strategy in which the best mobile phase is selected for validation studies. Optimized methods in MLC provide fast, efficient separations, thereby allowing the determination of a great variety of substances in a complex matrix. MLC is a useful technique for the identification of drugs in biological fluids, which often can be injected directly into the chromatographic system even in the presence of other compounds, including proteins, without any pretreatment other than filtration. In describing the many applications of MLC, this review draws upon examples taken from the literature as well as recent results of the authors' own research. It describes the theoretical approach, optimization strategy, and applications of MLC in the determination of different groups of drug substances. The compounds and matrices under discussion are: antidepressants in pharmaceuticals, calcium-channel blocking agents in serum, anserine and carnosine in meat samples, tyramine and tryptamine in wines, and sulfonamides in milk

Quantification of Tamoxifen in Pharmaceutical Formulations Using Micellar Liquid Chromatography

This paper describes a micellar liquid chromatographic method used to analyze tamoxifen (TAMO) in pharmaceutical formulations, while focusing in its interesting features. Solid samples were solved in a micellar solution, irradiated at 254 nm, filtered and injected. Extraction steps were avoided and thus expediting the procedure. Tamoxifen was resolved in <5 min, using a mobile phase containing 0.15 M sodium dodecyl sulfate–7% pentanol at pH 3, running at 1.5 mL/min under an isocratic mode at 40°C through a C18 column. Detection was achieved by fluorescence by excitation at 260 nm and emission at 380 nm. The validation was performed following the requirements of the International Conference on Harmonization (ICH) Tripartite Guidelines in terms of: specificity, sensitivity, calibration range (0.2 – 20 mg/L), accuracy (98.8 – 101.7%), precision (<1.5%) and robustness (<6.2%). The method was applied to quantify TAMO in TAMO citrate tablets supplied in Spain, and was found appropriate for the quality control of TAMO formulation

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

Management of diversity in master classroom: an increasing challenge for science education in valencian universities

Comunicació presentada a INTED2018, 12th International Technology, Education and Development Conference. (March 5-7, 2018, Valencia, Spain).Currently, many foreign students study a Master degree at the Valencian Universities. We can find students, which have immigrated to Spain in the recent years, and then have partially or fully follow the Spanish curricula (High School and/or Grade), and others which have come specifically to study the Master, attracted by the reputation of the Universities and the job and way-of-life offered by the country, and then have achieved their Grade in their countries. This has increased the diversity of the students in the classrooms, related to the ethnic origin, mother language, study practices, background and integration in the society. The present work gives an overview on how students and teacher manage the heterogeneity and diversity in a Master classroom related to chemistry. The term “diversity” is first detailed prior to discussing explicit studies. Different aspects of diversity are stated. The personal experience of the foreign students to adapt to the Spanish courses and environment was investigated. The actions taken by the lecturer to take advantage of diversity and minimize its negative effects were examined. A comparison between the academic results obtained by international and national students is given. Finally, the attention will be focused on language, study practices and background, since these dimensions are frequently discussed in the Valencian context. The implications and opportunities that offer diversity for national but also for international science research are presented

Design of the laboratory script by the students in chemistry practicals: Analysis of water

Comunicació presentada a INTED2018, 12th International Technology, Education and Development Conference. (March 5-7, 2018, Valencia, Spain).The laboratory practices during the Degree in Chemistry are currently designed so that the student must learn and execute a fully developed experimental protocol, previously written up by the professor, which contains all the information and requirements for the correct development of each laboratory session. Under these conditions, students do not need to take any initiative and, consequently, they do not put enough effort in reaching practical abilities with a well-based scientific criterion and do not try to think over the purpose of each lab operation, as well as the reason to use each material and/or each reagent. Thus, with the aim to promote a more active role of the students in their learning process and to improve their autonomy, a new laboratory practices design has been developed in this work, which follows methodologies on project-based cooperative learning: the students have been requested to elaborate themselves the laboratory script by pairs. With this innovative design, we pursue to involve the students in both elaboration and execution steps of the laboratory practicals, and then to increase their attention on them. Besides, the required bibliographic research would improve their knowledge about the studied topic and all aspects about the work at the laboratory. The practicals to-be-developed were related to the study of the physico-chemical quality of natural water, which has a high social relevance

An Innovative Project to Strengthen and Improve the Knowledge Acquisition in the Degree in Chemistry Using e-Learning Tools

Comunicació presentada a EDULEARN2018, 10th International Conference on Education and New Learning Technologies (July 2-4, 2018, Palma, Mallorca, Spain).The subject "Chemistry II (QU910)" is taught at first academic year (second semester) of the Degree in Chemistry at the University Jaume I. Some of its specific and general competencies are selflearning and writing and oral communication, regarding the main chemical concepts: chemical reactions, elements of the periodic table and calculations of the concentrations of the formed products and the remaining reagents in acid/base, complex, precipitation and redox reactions. We have noticed that 65% of the students have not studied any chemistry subjects (or only one) in High School or Professional Training before undertaking the Degree in Chemistry. The present project aims firstly to help these students to overcome their lack of background, secondly to compare the academic results of the students with and without previous contact with chemistry and finally, to establish actions to solve this prejudicial situation. This objective was reached by the implementation of a zero course, a course including the basic content of chemistry taught in the last years of High School, the month before the beginning of the first academic year. After the first year, students having attended chemistry before university obtained only 0.75/10 points more than the others. The Virtual Classroom, the emails and tutorial played an important role in the achievement of this zero-course

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

Implantación de las buenas prácticas de laboratorio en la asignatura "Química para las Ingenierias" en la Universitat Jaume I

Comunicación presentada en la V Jornada Nacional sobre Estudios Universitarios, celebrades en la Universitat Jaume I (Castellón, España), los dies 12 y 13 de Noviembre de 2015.En el presente artículo, se detalla la implementación de las Buenas Prácticas de Laboratorio (BPL) en el laboratorio de la asignatura «Química para las Ingenierías» (EX1006), impartida en varios grados de ingeniería (Agroalimentaria y del Medio Ambiente, Mecánica, Eléctrica, Tecnologías Industriales y Química) de la Universitat Jaume I. Las BLP son un conjunto de normas y procedimientos operativos acerca de la forma adecuada de organizar y trabajar en el laboratorio en una amplia variedad de disciplinas científicas, incluida la química. El principal objetivo de las BPL es asegurar la fiabilidad, estabilidad y calidad de los resultados. Para ello, se indica cómo el procedimiento experimental debe ser planificado, ejecutado, supervisado, anotado, registrado y archivado. Asimismo, proporciona recomendaciones para la gestión del laboratorio, en especial para minimizar el vertido de residuos tóxicos, e incrementar la seguridad laboral en el laboratorio. Varias organizaciones y agencias internacionales (industria farmacéutica, la Organización para la Cooperación y el Desarrollo Económicos, US Food and Drug Administration y la Comisión Europea), han desarrollado y promulgado varios conjuntos de normas BLP. La Universitat Jaume I considera que un conocimiento profundo y una aplicación adecuada de las BPL son muy importantes para desarrollar un trabajo correcto en el laboratorio químico. Por ello, los estudiantes de química deben ser conscientes desde el primer curso académico de su relevancia, así como conocer las normas principales y la forma de aplicarlas en el laboratorio. Por ello, las BPL se han incluido en la guía docente de la asignatura de Laboratorio de Química para las Ingenierías (1er curso académico) Además, los profesores deben centrarse en las BLP al impartir la docencia, para un correcto aprendizaje por parte de los estudiantes. Se requirió a los estudiantes que evaluasen el proceso de implantación y mostrasen su grado de aceptación de las BPL, mediante un cuestionario global de la asignatura. Como resultado final, se puede remarcar que los estudiantes comprendieron la utilidad de las BPL y la importancia de conocerlas para su futuro laboral, así como la necesidad de su inclusión en la guía docente de las asignatura de laboratorios de química

Use of Micellar Liquid Chromatography to Determine Mebendazole in Dairy Products and Breeding Waste from Bovine Animals

Mebendazole is an anthelmintic drug used in cattle production. However, residues may occur in produced food and in excretions, jeopardizing population health. A method based on micellar liquid chromatography (MLC) was developed to determine mebendazole in dairy products (milk, cheese, butter, and curd) and nitrogenous waste (urine and dung) from bovine animals. Sample treatment was expedited to simple dilution or solid-to-liquid extraction, followed by filtration and direct injection of the obtained solution. The analyte was resolved from matrix compounds in less than 8 min, using a C18 column and a mobile phase made up of 0.15 M sodium dodecyl sulfate (SDS)–6% 1-pentanol phosphate buffered at pH 7, and running at 1 mL/min under isocratic mode. Detection was performed by absorbance at 292 nm. The procedure was validated according to the guidelines of the EU Commission Decision 2002/657/EC in terms of: specificity, method calibration range (from the limit of quantification to 25–50 ppm), sensitivity (limit of detection 0.1–0.2 ppm; limit of quantification, 0.3–0.6 ppm), trueness (92.5–102.3%), precision (<7.5%, expressed at RSD), robustness, and stability. The method is reliable, sensitive, easy-to-handle, eco-friendly, safe, inexpensive, and provides a high sample-throughput. Therefore, it is useful for routine analysis as a screening or quantification method in a laboratory for drug-residue control

Analysis of thiabendazole, 4-tert-octylphenol and chlorpyrifos in waste and sewage water by direct injection – micellar liquid chromatography

A micellar liquid chromatographic method has been developed for the simultaneous quantification of the pesticides thiabendazole and chlorpyrifos, as well as an alkylphenol, which is included in pesticide formulations, i.e., 4-tert-octylphenol, in water. A sample was filtered and directly injected, avoiding large extraction steps using toxic solvents, thus expediting the experimental procedure. The contaminants were eluted without interferences in <17 min, using a mobile phase of 0.15 M sodium dodecyl sulfate – 6% 1-pentanol buffered at pH 3, running through a C18 column at 1 mL min−1 under the isocratic mode. This optimal mobile phase was selected using a statistical approach, which considers the retention factor, efficiency and peak shape of the analytes measured in only a few mobile phases. The detection was carried out by measuring absorbance at 220 nm. The method was successfully validated in terms of specificity, calibration range (0.5–10 mg L−1), linearity (r2 > 0.994), limit of detection and quantification (0.2–0.3; and 0.5–0.8 mg L−1, respectively), intra- and interday accuracy (95.2–102.9%), precision (<8.3%), and ruggedness (<9.3%). The stability in storage conditions (at least 14 days) was studied. The method was safe, inexpensive, produced little pollutant and has a short analysis time, thus it is useful for the routine analysis of samples. Finally, the method was applied to analyse wastewater from the fruit-processing industry, wastewater treatment plants, and in sewage water belonging to the Castelló area (Spain). The results were similar to those obtained by an already reliable method.This work was supported by the projects P1-1B2012-36 (Universitat Jaume I) and 11I358.01 (FACSA)