Search results for "Ammonium"

Separation of chelating agents as copper complexes by capillary zone electrophoresis using quaternary ammonium bromides as additives in N-methylforma…

2006

This study presents the use of quaternary ammonium bromides as additives in N-methylformamide (NMF) for the separation and quantification of chelating agents as copper complexes by capillary zone electrophoresis (CZE). The new quaternary ammonium bromides were synthesized in our laboratory and used for the first time for CZE applications performed in NMF media. The methods were developed and optimized for determination of six chelating agents (trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), nitrilotriacetic acid (NTA) and trieth…

Synthesis, Crystal Structure and Magneto‐Structural Correlation of an Unusual Thiocyanato‐Bridged Nickel( II ) Compound, [Ni(μ‐NCS)(dpt)(NCS)] 2 [Ni(…

2003

Reaction of Ni(ClO4)2·6H2O with bis(3-aminopropyl)amine (dpt) and ammonium thiocyanate produces the novel thiocyanato-bridged nickel(II) compound [Ni(μ-NCS)(dpt)(NCS)]2[Ni(μ-NCS)(dpt)(NCS)]4, which has been structurally characterised. The structure determination reveals that there are two different molecules in the crystal lattice; one is dinuclear and other is tetranuclear. Low-temperature magnetic measurements show that there are ferro- as well as antiferromagnetic interactions. The ferromagnetic interaction arises from the dinuclear part and the doubly bridged part of the tetranuclear unit; the antiferromagnetic interaction occurs between singly bridged nickel centres in the tetranuclear…

High-Temperature Ammonolysis of Uranium Trichloride and Tetrachloride

1965

Mixed microalgae culture for ammonium removal in the absence of phosphorus: Effect of phosphorus supplementation and process modeling

2014

Microalgal growth and ammonium removal in a P-free medium have been studied in two batch photobioreactors seeded with a mixed microalgal culture and operated for 46 days. A significant amount of ammonium (106 mg NH4-Nl(-1)) was removed in a P-free medium, showing that microalgal growth and phosphorus uptake are independent processes. The ammonium removal rate decreased during the experiment, partly due to a decrease in the cellular phosphorus content. After a single phosphate addition in the medium of one of the reactors, intracellular phosphorus content of the corresponding microalgal culture rapidly increased, and so did the ammonium removal rate. These results show how the amount of phos…

The conformational polymorphism and weak interactions in solid state structures of ten new monomeric and dimeric substituted dibenzyldimethylammonium…

2009

In this study, ten new dibenzyldimethyl/ethyl ammonium chloridopalladate(II) compounds with five different cations and two anions have been synthesized and a simple method for a synthesis, in which hydrochloric acid solutions are used, has been described. Furthermore, twelve structures including two polymorphs have been obtained from hydrochloric and methanol/acetonitrile solutions. The anion–cation and cation–cation interactions of the synthesized compounds have been studied mainly by means of single X-ray diffraction in order to study the effects of varying either the anion or the cations in these QA2PdCl4 and QA2Pd2Cl6 salts. The results indicate that the effects of intermolecular cation…

Hydrogen bond-stabilised N-alkylammonium resorcinarene halide cavitands

2010

A family of hydrogen bond-stabilised N-alkylammonium resorcinarene chloride and bromide cavitands were synthesised and characterised with 1H NMR and ESI mass spectrometry. The seven compounds exhibit interestingly either self-inclusion or guest complexation in the solid state evidenced by single crystal X-ray diffraction. The four dimers show self-inclusion of the upper rim propyl chains and consist of two hydrogen-bonded resorcinarene tetracations and six halide anions, while the remaining two halide anions are located in between the dimers linking them via hydrogen bonding. Small solvent molecules such as dichloromethane, methanol, n-butanol or chloroform are complexed into the resorcinar…

Microalgae cultivation in wastewater: nutrient removal from anaerobic membrane bioreactor effluent

2012

This study investigated the removal of nitrogen and phosphorus from the effluent of a submerged anaerobic membrane bioreactor (SAnMBR) by means of a lab-scale photobioreactor in which algae biomass was cultured in a semi-continuous mode for a period of 42 days. Solids retention time was 2 days and a stable pH value in the system was maintained by adding CO2. Nitrogen and phosphorus concentrations in the SAnMBR effluent fluctuated according to the operating performance of the bioreactor and the properties of its actual wastewater load. Despite these variations, the anaerobic effluent proved to be a suitable growth medium for microalgae (mean biomass productivity was 234 mgl(-1) d(-1)), achie…

Analysis of pyridoquinoline derivatives by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

2001

A method using liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) has been developed for the characterization and determination of pyridoquinoline derivatives 4,6-bis(dimethylaminoethylamino)-2,8,10-trimethylpyrido[3,2-g]quinoline, 4,6-bis(dimethylaminoethoxy)-2,8,10-trimethylpyrido[3,2-g]quinoline and 4,6-bis[(dimethylaminoethyl)thio]-2,8,10-trimethylpyrido[3,2-g] quinoline, all with potential antitumor properties. LC separation was performed on a conventional C18 column using a binary mobile phase composed of acetonitrile and 50 mM aqueous ammonium formate at pH 3. The APCI mass spectra obtained showed that proton addition giving [M + H]+ was the…

A new ionic liquid dimethyldinonylammonium bromide as a flow modifier for the simultaneous determination of eight carboxylates by capillary electroph…

2005

Two new methods of capillary zone electrophoresis based on aqueous phosphate running buffers with UV spectrophotometric detection were developed and optimized for the determination of eight carboxylates as copper complexes. Metalcomplexes are negatively charged, so measurements were made as anion analyses with flow reversal in the capillary. Two flow modifiers were used: a common tetradecyltrimethylammonium bromide (TTAB) and a new ionic liquid dimethyldinonylammonium bromide (DMDNAB). The methods were compared to each other. Better separation was achieved with DMDNAB as the flow modifier. Method development was done using a fused silica capillary (61 cm x 50 microm i.d.). Optimization was …

Solid-phase extraction of quaternary ammonium herbicides

2000

This paper highlights recent advances in the solid-phase extraction (SPE) of quaternary ammonium herbicides in water, soil, plant and biological samples. After a brief introduction summarizing the properties of quaternary ammonium herbicides and the difficulties involved in measuring them, attention is paid primarily to solid supports used for isolation and concentration, pre-treatments required for the different matrices, and eluents applied for quantitative desorption of these analytes. The determination techniques used after SPE and applications of the proposed SPE methodology are also briefly discussed.