Spectrophotometric and atomic absorption determination of Ni(II) in fresh and sea waters after preconcentration by flotation

A highly selective and sensitive procedure for flotation separation followed by spectrophotometric determination, confirmed by AAS, of Ni(II) traces is proposed. The maximum flotation separation (100%) is achieved at approximately 25 degrees C in the pH range of 1-3 using sodium diethyldithiocarbamate (as a collector) and oleic acid surfactant. The floated (1 : 2) colored complex is measured spectrophotometrically at 430 nm over a concentration range of 0.5-4.0 microg/g with a molar absorptivity of 0.44 x 10(4) L mol(-1) cm(-1). The procedure was successfully applied for the separation and determination of Ni(II) in fresh and sea waters.     

Quantification of multi-class antibiotics by UHPLC–MS/MS analysis combined with salt-assisted acetonitrile extraction: comparative evaluation of dairy and poultry manure

ABSTRACT

A comprehensive multiresidue method for the analysis of 33 antibiotics from 7 prevalent classes was comparably investigated for both dairy and poultry manure samples, which can be important pollution sources for the release of antibiotics into the environment. Following salting-out-assisted extraction with acetonitrile, the antibiotics were quantified with ultrahigh-performance liquid chromatography tandem mass spectrometry without a clean-up step. By changing the composition of the mobile phase for chromatography, a pronounced signal enhancement was achieved not only for tetracyclines (TCs) but also for other groups of antibiotics in the manure samples. Although the physicochemical properties of selected antibiotics were quite different, the apparent recovery values from dairy and poultry manure samples by using an extraction solvent comprising McIlvaine buffer and ethylenediaminetetraacetic solution at pH 3 were 86–121% and 89–113%, respectively. Apparent recovery of the antibiotics was not remarkably affected by the extraction solvent over a wide range of pH values, with the exception of the recovery of TC antibiotics from poultry manure, which was in the 53–55% range at pH 8. Furthermore, the poor performance of the analytical method for a few of the antibiotics in poultry manure was correlated with high metal and organic contents of the complicated matrix. The high suppression effects of co-eluted matrix components were compensated by constructing matrix-matched calibration curves and by using internal standards. Simultaneous quantification of seven different antibiotic classes with low limit of detection values varying from 0.38 to 31 μg kg^?1 for dairy manure and from 0.32 to 5.85 μg kg^?1 for poultry manure facilitated their monitoring. The application of the developed analytical method to dairy, broiler and layer-hen manure samples from confined animal feeding operations showed that a wide variety of antibiotics at high concentrations were found in broiler manure.     

Analysis of confocal microscopy image data of Physcomitrella chloroplasts to reveal adaptation principles leading to structural stability at the nanoscale

Proteins of the FtsZ (filamentous temperature-sensitive Z) family establish complex polymeric spatial patterns in plastids of the moss Physcomitrella patens. These structures represent a "plastoskeleton" that might contribute to plastid shape and stability. The aim of this work is to develop computer models of FtsZ network connectivity and dynamics. These computer models are developed from green fluorescent protein (GFP) images obtained by Prof. Reski's Plant Biotechnology group at the University of Freiburg by means of laser scanning confocal microscopy. Subsequently, structural reconstruction techniques based on cellular automata algorithm are applied on the raw image data to compensate for any information that is lost in the process of imaging. Segmentation of the processed data will result in the computer model of the targeted structures, which are used for further analysis. Model generation and experimental testing in the moss system is conducted in an iterative process with the aim of both forward and reverse biomimetics. A developed image processing algorithm with the aim of quantification of structural characteristics is utilized to extract structural features of the FtsZ network in Physcomitrella enabling us a statistical analysis on the extracted data. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Microwave‐Assisted Synthesis and Transformations of Cationic CpRu(II)(naphthalene) and CpRu(II)(naphthoquinone) Complexes

Details of the direct synthesis of cationic Ru(II)(η⁵‐Cp)(η⁶‐arene) complexes from ruthenocene using microwave heating are reported. Developed for the important catalyst precursor [Ru(II)(η⁵‐Cp)(η⁶‐1‐4,4a,8a‐naphthalene)][PF₆] reaction time could be shortened from three days to 15 min. The method was extended to [Ru(II)(η⁶‐benzene)(η⁵‐Cp)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐toluene)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐mesitylene)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐hexamethylbenzene)][PF₆], [Ru(II)(η⁵Cp)(η⁶‐indane)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐2,6‐dimethylnaphthalene)][PF₆], and [Ru(II)(η⁵‐Cp)(η⁶‐pyrene)][PF₆]. 1‐methylnaphthalene and 2,3‐dimethylnaphthalene afforded mixtures of regioisomeric complexes. [Ru(Cp)(CH₃CN)₃][PF₆], derived from the naphthalene precursor provided access to the cationic RuCp complexes of naphthoquinone, tetralindione, 1,4‐dihydroxynaphthalene, and 1,4‐dimethoxynaphthalene. Reduction of the tetralindione complex afforded selectively the endo,endo diol derivative. X‐Ray structures of five complexes are reported.     

Spektrographische Bestimmung von Hafnium in Zirkonium unter Verwendung einer Kohlendioxidzelle

Zusammenfassung Der steigende Bedarf an hafniumfreiem, metallischem Zirkonium machte die Entwicklung einer verläßlichen Methode zum Nachweis von Verunreinigungen des Zr durch Hf notwendig.Es wird eine spektrographische Methode beschrieben, bei der die Zirkonoxidproben durch einen Gleichstrom von 220 V und 9 Amp. angeregt werden; das gleichmäßige Brennen des Lichtbogens wird dabei durch Verwendung eines passenden Puffers gewährleistet.Die Proben werden in einer Zelle angeregt, in der während der Brenndauer des Lichtbogens eine CO₂-Atmosphäre aufrechterhalten wird. So wird der starke Hintergrund, der durch die Zirkonatome verursacht wird, unterdrückt, wodurch eine beachtliche Steigerung der Intensität der Hafniumlinien im Vergleich zum Hintergrund beobachtet wird. Die Methode gestattet eine quantitative Bestimmung des Hf in Zr für Konzentrationen von 0,95 bis 10%, wobei eine mittlere Abweichung von 2% nicht überschritten wird.Mit 4 Abbildungen     

Beiträge zur Papierchromatographie organischer substanzen. II

Zusammenfassung Es wird vorgeschlagen, organisch-präparative Mikromethoden auf Glasfaserpapier durchzuführen und die erhaltenen Reaktionsprodukte papierchromatographisch zu identifizieren. Ein hierfür entwickelter Mikroautoklav dient zur Durchführung der Umsetzungen auf Glasfaserpapier in der Hitze. Eine einfache Eluierungsapparatur erlaubt, die Reaktionsprodukte zu reinigen, zu eluieren und auf normales Chromatographiepapier zu übertragen. Außerdem können in dieser Eluierungsapparatur Mikromengen auf Glasfaserpapier aufgebrachter Substanzgemische durch fraktionierte Eluierung mit verschiedenen Lösungsmitteln nach ihrer Löslichkeit getrennt werden.

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Summary It is suggested that organic preparative micro methods be conducted on glass fiber paper, and that the resulting reaction products be identified by paper chromatography. A micro autoclave developed for this purpose serves for carrying out the reactions at high temperatures on glass fiber paper. A simple eluting apparatus permits the reaction products to be purified, eluted, and transferred to ordinary Chromatograph paper. Furthermore, micro quantities of mixtures of substances brought onto glass fiber paper can be separated in this elution apparatus by fractional elution with various solvents according to their solubility.

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Résumé Les auteurs proposent d'effectuer des micro-préparations organiques sur du papier de fibre de verre et d'identifier par Chromatographie sur papier les produits de réaction obtenus. A cette fin un micro-autoclave a été mis au point pour permettre d'effectuer des réactions à chaud sur papier de fibre de verre. Un appareil d'élution simple permet de purifier les produits de réaction, de les diluer et de les transposer sur un papier chromatographique normal. En outre, il est possible de séparer avec cet appareil, par élution fractionnée, des micro-quantités de mélanges de substances obtenus sur papier de fibre de verre en fonction de leur solubilité, à l'aide de différents solvants.

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Teile der DissertationA. Kabil, Technische Hochschule Wien 1958.     

Atomic Absorption Spectrophotometric Determination of Selenium

An atomic absorption method has been developed for the determination of selenium in synthetic mixtures of geological samples. Thiourea and n-butylamine are added as a matrix modifier for the precise and accurate determination.     

Atomic Absorption Spectrophotometric Investigation and Determination of Palladium

This work aims to achieve a determinate characterization of compound formation and to find out the resolution to overcome chemical interferences in atomic absorption spectrophotometric (AAS) determination of palladium. The effect of flame composition in producing a neutral palladium atoms was investigated. A new analytical procedure has been elaborated for the determination of palladium.     

Orthogonal multifunctionalization of aliphatic polycarbonate via sequential Michael addition and radical‐thiol‐ene click reactions

Aliphatic polycarbonate (PC) copolymer is synthesized by ring opening copolymerization of acrylate‐ and allyl‐functional cyclic carbonate monomers. The post‐polymerization functionalization of the resulting copolymer is performed quantitatively using a variety of thiol compounds via sequential Michael addition and photo‐induced radical thiol‐ene click reactions within relatively short reaction time at ambient temperature. This metal‐free click chemistry methodology affords the synthesis of biocompatible PC copolymer with multifunctional groups. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1581–1587