Search results for "ammonium"

Cotton swabs supported in-situ assay for quaternary ammonium compounds residues in effluents and surfaces

2018

Abstract Cellulose paper and cotton swabs have been tested as sampling, reaction and measurement media for quaternary ammonium compounds (QACs) using the reagent Chromo Azurol S in the presence of aluminum cations (CAS-Al). On the basis of the results obtained a new method is proposed for the analysis of QACs in water samples which only entails the successive immersion of swabs into 1 mL of the samples, 1 mL of a solution of CAS-Al for the formation of a ternary blue complex, and 1 mL of water to remove the excess of reagent. The method can be used for the visual on site detection of QACs in effluents, as well as for their quantification within the 3.62–36.2 mg/L range through the direct me…

General approach for the analysis of various alkaloid classes using capillary electrophoresis and capillary electrophoresis-mass spectrometry

1997

Abstract The analysis of various alkaloid classes employing capillary electrophoresis (CE) and on-line combined CE-mass spectrometry (CE-MS) is described. A CE method is presented for the analysis of alkaloids without derivatisation or purification. The separation of four different groups of alkaloids consisting of monoterpenoid indole alkaloids, protoberberines/benzophenanthridines, β-carboline alkaloids, and isoquinolines from poppy by free zone capillary electrophoresis has been obtained using a 1:1 mixture of 100 mmol 1 −1 ammonium acetate (pH 3.1) and acetonitrile. The influence of alkaloid structure on the electrophoretic mobility is discussed. The CE-MS reconstructed total ion curren…

The Cation as a Tool to Get Spin-Canted Three-Dimensional Iron(III) Networks

2004

Alkyl-substituted ammonium cations (X) allow the preparation of a series of spin-canted oxo- and oxalato-bridged three-dimensional iron(III) networks, exhibiting magnetic ordering at T(c) values ranging from 40 to 56 K. The value of T(c) varies with the cation despite the lack of significant structural modifications.

Complexes of organometallic compounds

1974

Abstract Tetraphenylarsonium and tetramethylammonium salts of the complex anions Ph 3 Pb(N 3 ) − 2 , Ph 3 Pb(N 3 )(NCS) − , Ph 2 Pb(N 3 ( 2 − 4 )) and Ph 2 Pb(N 3 )(NCS) − 2 have been prepared and characterized. Infrared spectra and solution conductance data are reported. Possible configurations of the complex anions are discussed.

Cu2+-cyclam complex functionalised with naphthylmethyl fluorescent signalling subunits as fluorescent chemosensors for sulfate in aqueous environment.

2000

Abstract The fluorescent behaviour of the polyazacycloalkane containing naphthyl groups 1,4,8,11-tetrakis(naphthylmethyl)-1,4,8,11-tetraazacyclotetradecane (L 1 ) and its Cu 2+ complex in the presence of anions are compared in aqueous environment (THF:water 70:30 v/v, 0.1 mol dm −3 tetrabutylammonium perchlorate, 25°C). The emission fluorescent intensity of the L 1 –Cu 2+ system is selectively enhanced in the presence of sulfate at acid pH.

Novel route in the synthesis of MCM-41 containing framework aluminum and its characterization

1999

Abstract Mesoporous molecular sieve MCM-41 with incorporated structural aluminum (Al-MCM-41) was prepared by hydrolysis of a solution of tetraethoxysilane and aluminum isopropoxide in the presence of ammonia as a catalyst. This method provides Al-MCM-41 of different Si/Al ratios from 13 to 297 corresponding to 0.3–7 mol% Al within an hour. X-ray diffraction and nitrogen adsorption measurements showed that the Al-MCM-41 prepared by this method had a highly ordered structure of pore arrays. Most Al atoms in these samples were incorporated tetrahedrally in the MCM-41 structure, which gave rise to cationic sites in the framework.

Hierarchical Ordering in Ternary Co-Crystals of C60, N-Benzyl Ammonium Resorcinarene Bromide and Solvent Molecules

2014

Co-crystallization of C60 together with an N-benzyl ammonium resorcinarene bromide from toluene:1,2-dichloroethane mixture results in ternary co-crystals where the modulated C60 lattice entraps dimeric resorcinarene assemblies, which, in turn, have 149 and 280 A3 cavities filled with 1,2-dichloroethane molecules.

Oxidative dehydrogenation of n-butane on MgO-supported vanadium oxide catalysts

1998

Abstract Vanadium–magnesium oxide (VMgO) catalysts have been prepared, characterized and tested in the ODH of n-butane. The catalysts were prepared by two variations of the wet-impregnation method using aqueous ammonium metavanadate or organically-based methanolic vanadyl acetylacetonate solutions. The catalyst surface area depends on the vanadium content and the preparation method. Catalyst characterization (i.e. XRD, 51V NMR, FTIR, LRS) results indicate the presence of poor crystalline Mg-orthovanadate (Mg3V2O8), while the presence of other Mg-vanadates is not clear. Oxygen isotopic-exchange experiments on VMgO catalysts indicate an R2 process: [ 18 O 2 +2 16 O 2− (s) → ( 18 O 18 O 16 O 1…

Ammoniates of Uranium Trichloride and Tetrachloride

1965

Bioproduction of an extract from Penicillium funiculosum Thom with activity against Ceratitis capitata and Tetranychus urticae

1993

The bioproduction conditions of a crude extract from a strain of Penicillium funiculosum Thom, which shows activity against Ceratitis capitata and Tetranychus urticae, have been optimized. The efficacy degree was 95% (C. capitata) and 100% (T. urticae), according to Abbot. This is the first report on the pesticide activity of an extract from P. funiculosum against these species. The best yields were obtained when P. funiculosum was grown in Raulin-Thom medium at pH 6.5 with sucrose candy as the carbon source and ammonium sulphate and phosphate as the nitrogen source. Other favourable conditions were static cultures, at 28 degrees C, and in the dark.