SummaryIon-exclusion chromatography (IEC) and capillary electrophoresis (CE) have been compared for determination of organic acids in samples of Sherry wine vinegar. The accuracy of each technique was evaluated by use of the standard addition method. There were no differences belvveen the techniques at a significance level of 5%, except for determination of malic acid by CE. Both analytical methods were used to analyse sixteen samples of Sherrywine vinegar supplied by different producers. The regression coefficients (r ~) for analysis by IEC and CE exceeded 0.94 for all acids. Results from both methods were in good agreement and the methods are sufficiently selective and sensitive to be applied directly to sherrywine vinegars.

Changes in the content of low molecular weight phenolic compounds (hydroxybenzoic and hydroxycinnamic acids, aldehydes, and their esterified derivatives, tyrosol and 5-(hydroxymethyl)-2-furaldehyde) during the aging of three different classes of Sherry wine, Fino, Oloroso, and Amontillado, have been studied. The samples studied were taken from each of the scales of the particular aging system applied to the three classes of wine. Clear differences were observed in the behavior of the low molecular weight phenolic in the three classes of wine. The wines subjected to oxidative aging presented a higher phenolic content overall, with the exception of the esterified derivatives of phenolic compounds that are mainly found in the samples that have not undergone any process of oxidation. MANOVA results confirmed that there are significant differences between all of the samples of the three types of wines. Using LDA, a classification of 100% of the samples has been made.

SummaryA capillary electrophoretic method, with divalent cations as complexing agents in the electrolyte, has been developed for separation and determination of the low molecular weight organic acids most commonly found in wine, viz. formic, fumaric, succinic, oxalic, mahc, tartaric, acetic, lactic, and citric acids. The separation conditions optimized were electrolyte concentration, organic flow modifier concentration, type and concentration of complexing agents in the electrolyte, and injection time. The best resolution of some of the acids studied was achieved by use of an electrolyte containing tetraborate buffer (10 mM) at pH 9.3, an organic flow modifier (tetradecyltrimethylammonium hydroxide), and Ca 2+ (10 ppm) and Mg 2+ (10 ppm) as complexing agents. Other conditions used in the method were hydrostatic injection (10 cm height for 30 s), detection at 185 nm, and temperature 20 ~ For all the acids studied detector response was linear for the concentration ranges considered. The repeatability of each point on the calibration plot for standards (n = 4)was generally better than 1%. The method was applied to samples of must, wine, brandy, and vinegar from the Jerez region.

RESUMENSe realizó una completa serie de encuestas personales a alumnos de la Facultad de Ciencias de la Universidad de Cádiz, con el objeto de conocer las causas por las que dejan de asistir a las clases presenciales. El estudio realizado permite hacer un análisis detallado de los motivos apuntados por el conjunto de la población encuestada así como discriminar un grupo especial de alumnos de baja asistencia, con particularidades significativas.ABSTRACTA complete personal inquiry were carried out to know the real causes for students from a Science Faculty (University of Cádiz) to fail attending their classes. The current study allows to analyze the causes pointed by the general group as well as to distinguish a particular group of students classified as low attendance.

RESUMENEn este artículo se intenta dar a conocer el proyecto Brújula, una iniciativa de tutorización en la Facultad de Ciencias de la Universidad de Cádiz. Se analizan las motivaciones que hicieron posible su puesta en funcionamiento, cómo se ha desarrollado, y se analizan los resultados obtenidos en estos tres primeros años de vida.ABSTRACTThis paper presents the Brújula Project, a guidance program performed by the Faculty of Science, from University of Cadiz. The facts which motivate its beginning will be analysed, and besides the development and the results obtained through these last three years.