Determination of End-Points in Hydrolytic Potentiometric Titrations in the Ca2+ - F- System

Mathematical modelling of a multi-component titration system of hydrolytic titrations of metal ions is described. A comparison of the calculated and experimental titration curves and end volumes in the Ca2+ -F_ system at different pH values of titrated solutions is presented. The determination of the end-point of titrations by several approximation and mathematical methods is described

Diversity for olive oil composition in a collection of varieties from the region of Valencia (Spain)

Olive (Olea europaea) has a long history of cultivation in the Mediterranean region of Valencia (Spain) and many local varieties exist in the area. According to their economic importance, varieties are classified as National, Principal, Secondary, Local, Disseminate, and Minor. We have evaluated during four seasons the olive paste moisture content, fat content, and olive yield, and the olive oil acidity, peroxide index, K232 and K270 parameters, total phenolics, K225 parameter, and fatty acids content in 45 varieties from the Collection of Olive Varieties from the Region of Valencia. Considerable diversity existed among varieties for all traits studied, and the variety effect was much greater than the season effect. Wide ranges of variation have been found for most traits, with differences among varieties being of more than 10-fold for total phenolics. The coefficient of genetic variation and heritability values have been generally high, in particular for fatty acids content. A few varieties were found to present values outside the ranges established in the regulations for several olive oil composition traits, although in some cases, like a variety with above the limit content of oleic acid, they are of interest for breeding. Several correlations were found to be significant between the K232 index and fatty acids profile, in particular with oleic acid. The values obtained for variety averages as well as the principal components analysis show that economically relevant varieties present a lower diversity for composition than varieties with low economic importance. In this respect, selection among traditional materials can be of interest to recover neglected varieties with specific composition profiles, as well as to identify sources of variation for breeding programmes. Discriminant analysis allowed a correct classification of 99.4% of samples, showing that composition profiles, in particular fatty acids content, is a powerful tool for chemometry and fingerprinting of olive oil. Overall, the results show that the wide diversity found in the collection studied, in particular in the less economically important varieties, is of interest for the selection and breeding of olive varieties with improved quality.Authors are grateful to Sergio Paz (Instituto Valenciano de Investigaciones Agrarias, Moncada, Spain) for his technical help, and also to the Laboratorio Agroalimentario de la Conselleria de Agricultura, Pesca, Alimentacion y Agua of the Generalitat Valenciana for the providing the facilities and funds for this research.Ruiz Dominguez, ML.; Raigón Jiménez, MD.; Prohens Tomás, J. (2013). Diversity for olive oil composition in a collection of varieties from the region of Valencia (Spain). Food Research International. 54(2):1941-1949. doi:10.1016/j.foodres.2013.06.023S1941194954

Discrimination of n-3 Rich Oils by Gas Chromatography

Exploring the capabilities of instrumental techniques for discriminating n-3 rich oils derived from animals is a very important though much neglected area that was emphasized more than 100 years ago. In this study the potential of gas chromatography (GC) for discriminating full fatty acid methyl ester (FAME) profiles from fish (cod liver and salmon) and marine mammal (seal and whale) oils is evaluated by means of principal component analysis (PCA). The FAME profiles from plant oils such as rapeseed, linseed and soy oils and seven different brands of n-3 supplements are also used in the discrimination process. The results from the PCA plots can reliably distinguish between plant, n-3 supplements, fish and marine mammal oils. By removing the contribution of the n-3 supplements and plant oils it is possible to discriminate between types of fish and marine animal oils. GC offers a rapid, simple and convenient means of discriminating oils from different species, brands and grades

Changes in the Lower Drava River Water Quality Parameters Over 24 Years

The goal of this study was to analyse 13 physico-chemical and microbiological parameters of the Drava River water at three sampling sites in the lower Drava region (eastern Croatia) over two distinct periods: the pre-war period between 1985 and 1992 and the post-war period between 1993 and 2008. Over both periods, most parameters kept within the tolerable water quality limits, while NO3-N, NH4-N and BOD5 were higher. The lower Drava showed slight organic pollution with high concentrations of dissolved oxygen. High levels of total coliforms and heterotrophic bacteria in the post-war period were only found downstream of the town of Osijek. Upstream of Osijek, the river showed a tendency for improvement.prostornih i vremenskih promjena tijekom perioda od 24 godine. Analizirali smo 13 fi zikalno-kemijskih i mikrobioloških parametara vode rijeke Drave na tri mjerne postaje smještene na području donjeg toka Drave (istočna Hrvatska) tijekom dvaju različitih razdoblja: 1985.-1992. (period prije rata) i 1993.-2008. (period poslije rata). Iako su vrijednosti većine podataka prikupljenih tijekom dvaju promatranih razdoblja oscilirale, vrijednosti su im se još uvijek nalazile u granicama za I. i II. vrstu voda. Vrijednosti nekih fi zikalno-kemijskih varijabla, kao što su NO3-N, NH4-N i BPK5 još su uvijek iznad granice za II. vrstu. Rezultati ovog istraživanja pokazali su blago organsko onečišćenje vode rijeke Drave s visokim koncentracijama otopljenog kisika. Povećanje broja ukupnih koliformnih i heterotrofnih bakterija u poslijeratnom razdoblju veliki je problem u području nizvodno od Osijeka pri čemu njihov broj katkad dostiže i vrijednosti za V. skupinu površinskih voda. Rezultati analize kvalitete vode rijeke Drave u dva različita razdoblja na dva mjerna mjesta uzvodno od Osijeka upućuju na tendenciju poboljšanja, iako neki od promatranih parametara pokazuju vrijednosti više od onih za II. skupinu riječnih voda. Različitosti, odnosno sličnosti među mjernim postajama istražene su metodom klasterske analize