Luciana Gabrielli Favretto

Molecular weight fractionation of polyethylene gylcol by gas chromatography

Abstract The author carried out temperature-programmed, gas chromatographic, molecular-weight fractionation of various derivatives of polyethylene glycol, with the general formulae RO(CH2CH2O)nR (R  Me, Ph, TMS) and R(CH2CH2O)nCH2CH2R (R  Cl, PhS), in order to determine which derivative has the highest volatility and thermal stability and the lowest energy of adsorption on the support, thus making it the most suitable for the routine analysis of polyethylene glycol product with a molecular weight of less than 1000. Although the dimethyl derivatives are the most volatile, the bis-trimethylsilyl derivatives are the most suitable for the analysis of polyethylene glycol by GLC under the conditions used.

Principal component analysis for the identification of pollution sources in mussel survey by trace metals

ZusammenfassungDie Analyse der Hauptkomponenten wurde auf die Korrelationsmatrix, die aus der 8 × 43-Datenmatrix hervorgeht, angewandt. Diese 8 Spurenmetalle sind Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb, die im Fleisch der Miesmuscheln (Mytilus galloprovincialis Lamarck) gefunden worden sind. Die Miesmuscheln stammen aus zwei Gegenden des Golfes von Triest. Vier Hauptkomponenten erklären 76–78 % der totalen Varianz der beiden Stichproben. Die orthogonale-rotierte Faktorenmatrix zeigt, daß Co und Ni an die erste Hauptkomponente und Cd und Pb an die erste (Lage 2) oder an die zweite Hauptkomponente (Lage 1) gebunden sind. Die Herkunft der Spurenmetalle im Muschelfleisch aus dem Golf von Triest wird diskutiert.SummaryPrincipal component analysis has been applied to analyze the correlation matrix obtained from a 8 × 43 data matrix. The 8 trace metals are Mn, Co, Ni, Cu, Zn, Cd, Hg, Ph, which are contained in the soft part of mussels (Mytilus galloprovincialis Lamarck). Mussels were sampled from two sites in the Gulf of Trieste. In both samples, 76–78% of the total variance is explained by the four principal components. The orthogonally rotated factor matrix indicates that Co and Ni are bonded to the first principal component and Cd and Pb to the first (site 2) or second principal component (site 1). The origin of trace metals in the soft part of mussels from the Gulf of Trieste is discussed.

Multivariate data analysis of sea waters and mussels in relation to pollution sources of trace elements

ZusammenfassungDer Gesamtgehalt von Cu, Zn, Pb in den oberen Schichten des Seewassers aus der Bucht von Muggia (Golf von Triest) wurde nach einer puls-inversvoltammetrischen Methode untersucht. Es wurden die Beziehungen dieser Spurenelemente zu den bekannten Verunreinigungsursachen diskutiert. Weiterhin wurde der Gehalt von Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb im Fleisch von Miesmuscheln (Mytilus galloprovincialis Lamarck) untersucht. Die Mollusken stammen aus der Umgebung des Hafens von Triest, in der Nähe eines wichtigen Abwasserkanals. Die Korrelationsmatrix geht aus der 8 × 43-Datenmatrix nach einer logarithmischen Transformation der Konzentrationsvariablen hervor, dies basiert auf der Analyse der Hauptkomponenten. 8 Variable wurden auf 4 Hauptkomponenten, die 80% der totalen Varianz erklären, reduziert. Die orthogonal-rotierte Faktorenmatrix zeigt, daß Co, Ni, Cd und Pb an die erste Hauptkomponente, Cu und Zn an die zweite, Hg an die dritte und Mn an die vierte Hauptkomponente gebunden sind. Die Ergebnisse dieser Forschung werden mit denen vorhergehender mehrdimensionaler Analysen aus zwei Gegenden in der Bucht von Muggia verglichen. Die Herkunft der Spurenelemente im Muschelfleisch aus dem Golf von Triest werden diskutiert.SummaryThe total concentration of Cu, Zn and Pb in surface sea waters from the Bay of Muggia (Gulf of Trieste, Northern Adriatic Sea) was determined by anodic stripping voltammetry. The association of these trace elements in relation to the known sources of pollution was discussed. The content of eight trace elements (Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb) in the soft part of mussels (Mytilus galloprovincialis Lamarck) is also considered. The wild molluscs were sampled in the harbour of Trieste, in the proximity of an important city sewer. Principal component analysis was used to analyse the correlation matrix obtained from an 8 × 43 data matrix after a logarithmic transformation of the concentration variables. Eight variables were reduced to four principal components, which explained 80% of the total variance. The orthogonally rotated factor matrix shows that Co, Ni, Cd, and Pb are associated with the first principal component, Cu and Zn to the second, Hg to the third and Mn to the fourth principal component. The results of this multi-variate data analysis are compared with those already obtained from two sampling sites in the Bay of Muggia and the origin of some trace metals in the soft part of mussels from the Gulf of Trieste is discussed.

Principal component analysis as a tool for studying interdependences among trace metals in edible mussels from the gulf of Trieste

ZusammenfassungDie Hauptkomponentenanalyse wurde auf die Korrelationsmatrix, die aus der (6 × 44) Datenmatrix hervorgeht, angewandt. Die 6 Spurenmetalle sind Co, Ni, Cu, Cd, Hg, Pb, die im Miesmuschelnfleisch (Mytilus galloprovineialis Lamarck) gefunden werden. Die Miesmuschelnproben stammen aus der Zucht des Golfes von Triest. In dem Eigenvektorraum werden die Dimensionen auf drei Hauptachsen reduziert, die ungefähr 77% der totalen Varianz erklären.Die unrotierte Faktorenmatrix, die aus den Hauptkomponenten hervorgeht, zeigt, daß Co, Ni, Cu an die erste Hauptkomponente, Cd und Pb an die zweite, Hg an die dritte gebunden sind. Dieses Bild wird von der Varimax-rotierten Matrix bestätigt und es findet eine Erklärung in der Herkunft der Spurenmetalle.SummaryPrincipal component analysis has been applied to analyze the correlation matrix obtained from a (6 × 44) data matrix. The 6 trace metals are Co, Ni, Cu, Cd, Hg, and Pb, which are contained in the soft part of edible mussels (Mytilus galloprovincialis Lamarck) from a hatchery on the gulf of Trieste. In the space of “eigenvectors”, the dimensions are reduced to 3 principal axes, which account for about 77% of the total variance.The unrotated factor matrix obtained by the principal components shows that Co, Ni and Cu are bonded to the first principal component, Cd and Pb to the second, Hg to the third. This picture is also assessed by the Varimax-rotated matrix and it is tentatively explained, at least in part, by considering the associations of the trace metals from various geographical sources.

Preliminary investigation on the balance of lead and cadmium content in milk and its by-products

ZusammenfassungVor kurzem sind viele Untersuchungen zur Bestimmung von Blei und Cadmium in der Milch wegen ihrer Giftigkeit und wegen der Bedeutung der Milch in der Ernährung der Säuglinge und Kinder durchgeführt worden. Bei einigen Milchprodukten wurde eine Anreicherung sowohl von Blei als auch von Cadmium festgestellt.Aus diesem Grund sind Milch und Milcherzeugnisse (Magermilch, Rahm und Käse) aus dem gleichen Ansatz systematisch untersucht worden, um eine Bilanz des Gehalts solcher Metalle aufzustellen. Blei und Cadmium wurden durch Atomabsorptionsspektrometrie und Graphitrohr in einer Lösung der veraschten Untersuchungsproben bestimmt. Wegen der Interferenzen durch den Einfluß der Matrix wurde die Methode der Standard-Zusätze gewählt, damit die Metalle in einigen Proben mit einer statistisch vertretbaren Genauigkeit festgestellt werden konnten. Die Grenzen des Blei- und Cadmiumgehalts in den obenerwähnten Produkten entsprechen denen, die von der neuesten Literatur über nicht verseuchte Proben angegeben wird.SummaryMany studies have recently been devoted to the determination of lead and cadmium in milk, in view of the toxicity of these metals and the importance of milk in the diet of infants and children. Enrichment of lead and cadmium in fatty dairy products has been sometimes noted.A systematic study on milk and its primary products (skimmed milk, cream and cheese) obtained from the same batch of milk is considered in order to define a tentative balance of these two metals. Lead and cadmium were determined by atomic-absorption spectraphotometry with graphite furnace on a solution of the ashed sample. As a consequence of the appreciable interference due to the matrix effects, the method of standard additions was adopted to determine the metals in few samples with a statistically acceptale degree of accuracy and precision. The range of the lead and cadmium content found in these products is comparable with recent literature data concerning uncontaminated samples.

Chemoenzymatic synthesis and antimicrobial activity evaluation of monoglucosyl diglycerides

Monogalactosyl diglycerides with medium to long fatty acid acyl chains, were prepared and examined for antimicrobial activity against Gram positive, Gram negative bacteria and fungi. The study of their in vitro antimicrobial activity confirms the significant activity of some monogalactosyl diacylglycerol analogues and establishes for the galactose series that the 1,2-disubstitution and the octanoyl chain are the proper structural features for the maximum activity.

Multivariate Data Analysis of Some Xenobiotic Trace Metals in Mussels from the Gulf of Trieste

ZusammenfassungDer Gehalt von Cd, Hg und Pb in Miesmuschelfleisch wurde nach einer statistischen mehrdimensionalen Analyse untersucht. Besonders wurde die Hauptkomponentenanalyse zum Studium der Assoziationen dieser toxischen Metalle in Miesmuscheln angewandt. Die Miesmuschelproben stammten aus dem Golf von Triest, ein kritisches Gebiet für Quecksilberverunreinigungen.SummaryThe concentration of Cd, Hg and Pb in the soft part of mussels has been studied by means of bi-and multi-variate statistical approaches. In particular, the principal component analysis has been applied to study the association among these toxic metals in mussels sampled from the gulf of Trieste, which is a critical area as far as mercury pollution is concerned.

Heavy metals at trace level in edible mussels (Mytilus galloprovincialis Lamarck) from the gulf of Trieste.

ZusammenfassungDie Gehalte der Schwermetalle (Kobalt, Nickel, Kupfer, Cadmium, Quecksilber und Blei), die im Fleisch der Miesmuscheln (Mytilus galloprovincialis Lamarck) aus der Zucht des Golfes von Triest gefunden werden, haben eine Normal- oder Log-Normal-Verteilung beim statistischen Test, der für die Asymmetrie der Verteilung empfindlich ist. Eine Log-Normal-Verteilung beschreibt fast alle Spurenmetalle, besonders toxische Schwermetalle, wie Cadmium, Quecksilber und Blei. Die positive Asymmetrie der Verteilung dieser Metalle ist ähnlich, obwohl die Varianzanalyse nach einfacher Klassifikation angibt, daß der Mittelwert der Stichprobenverteilung aus verschiedenen Gesamtheiten kommt, welche die einzelne Zucht kennzeichnen.SummaryThe concentration of heavy metals (cobalt, nickel, copper, cadmium, mercury and lead), which are present at trace levels in the edible part of mussels (Mytilus galloprovincialis Lamarck) from hatcheries in the gulf of Trieste, is normally or log-normally distributed, according to a statistical test sensitive to asymmetry of the distribution. A log-normal distribution appears valid for describing nearly all trace metals, in particular toxic heavy metals like cadmium, mercury and lead. The frequency distribution of these metals has nearly the same asymmetry, although the one-way analysis of the variance shows that sample means come from different population means characterising the particular hatchery.

Comparison between gas—liquid chromatography and column chromatography in the determination of the molecular weight distribution of polyethylene glycol derivatives

Abstract In the determination of the molecular-weight distribution of polyethylene glycol derivatives, with the formula RO(CH2CH2O)nR, R = p-(1,1,3,3-tetramethylbutyl)-phenyl, the fractionation by temperature-programmed gas—liquid chromatography gives accurate results up to n = 7 (mol. wt. 702.3). This could be confirmed by comparing the results with those obtained by linear elution absorption chromatography, which allows accurate fractionation at least up to n = 12 (mol. wt. 922.5).

High-performance liquid chromatography of carotenoids from some marine shellfish

The chromatographic profiles of carotenoids from some marine shellfish are reported. The analyses were performed both by gradient elution reversed-phase and isocratic direct phase high-performance liquid chromatography (HPLC), and the results obtained are compared and discussed. The six main carotenoids extracted from three shellfish species (Chlamys opercularis, L., Cardium tuberculatum, L., Pecten jacobaeus, L.) were isolated in highly pure form by means of semi-preparative HPLC. They were characterized by means of spectroscopic methods (visible absorption and infrared spectroscopy), and chemical tests: the identification of fucoxanthin and alloxanthin was possible while a tentative identification of two other carotenoids (fucoxanthinol and diatoxanthin) was suggested. Carotenoids in clams and scallops were present both in esterified and free form, while in cardia only carotenoid esters were detected.