Search results for "liquid"

Simultaneous Automated Determination of Catecholamines, Serotonin, and Their Metabolites in Brain Tissue by HPLC and Electrochemical Detection

1993

Abstract A robust procedure with minimal tissue sample pretreatment, based on reversed-phase, ion-pair high performance liquid chromatography (HPLC) combined with electrochemical detection has been developed for the automated and simultaneous determination of the biogenic amines norepinephrine (NE), epinephrine (E), dopamine (DA), 5-hydroxytryptamine (5-HT) and their metabolites 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG), 3,4-dihydroxyacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindolacetic acid (H I A A) in as little as 0.5 mg brain tissue. The chromatographic conditions remain stable for at least 8 weeks. In particular small amounts of samples which do not allow reexamina…

Sensitive and selective determination of metabolically formed trans -dihydrodiols and phenols of benzo[ a ]pyrene in water and urine samples by HPLC …

1998

A method has been developed to separate hydroxylated metabolites of the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene, i. e. trans-4,5-, 7,8-, 9,10-dihydrodiol and 1-, 3-, 7-, and 9-phenol, by HPLC with amperometric detection employing an isocratic methanol/water eluent (70:30, v/v) containing 0.5 g/L sulfuric acid and 1 g/L lithium perchlorate. Compared with the usually applied fluorescence (λex = 265 nm, λem = 460 nm) and ultraviolet (λ = 265 nm) detection, the amperometric technique is about 2–12 times more sensitive for the determination of all metabolites investigated. The method was applied to the determination of the seven metabolites of benzo[a]pyrene in different wate…

When Chlorides are the Most Reactive: A Simple Route towards Diverse Mono- and Dicationic Dimethyl Phosphate Ionic Liquids

2014

Structurally diverse aromatic and aliphatic ionic liquids have been prepared via anion metathesis utilizing alkylammonium chlorides and trimethyl phosphate. Excellent oxygen-containing functional-group tolerance in preparation of potentially greener dimethyl phosphate ionic liquids has been demonstrated. For the first time, this method has been employed in the synthesis of dicationic imidazolium-based ionic liquids possessing a dimethyl phosphate counterion, providing a simple, direct route towards structurally novel products of high purity.

Imidazolsynthesen, Mitt. Synthese α-substituierter 4(5)-Methoxymethyl-5(4)-methyl-imidazole

1977

Methoxymercurierung der α,β-ungesattigten Ketone 1 ergibt α-Acetoxymercuri-β-methoxy-ketone 2, die direkt zu α-Brom-β-methoxy-ketonen 3 bromo- demercuriert werden. Cyclisierung von 3 mit Formamidinacetat in flussigem Ammoniak fuhrt zu α-substituierten 4(5)-Methoxy-methyl-5(4)-methyl-imidazolen 4, deren Struktur 13C-NMR-spektroskopisch gesichert ist. Synthesis of α-Substituted 4(5)-Methoxymethyl-5(4)-methylimidazoles Methoxymercuration of the α,β-unsaturated ketones 1 produces the α-acetoxymercury-β-methoxyketones 2, which are bromo-demercurised without isolation to give the α-bromo-β-methoxyketones 3. Cyclisation of 3 with formamidine acetate in liquid ammonia leads to α-substituted 4(5)-me…

1987

X-ray measurements of stretched crosslinked liquid-crystalline side group polymers show that two types of orientation of the mesogenic groups relative to the polymer chains (parallel or perpendicular) are possible, depending on the structure of the polymer chain. For two liquid-crystalline polymethacrylates with long spacer groups (6 methylene units) the mesogenic groups orient preferably perpendicularly to the polymer chains (axis of strain). For three liquid-crystalline polyacrylates with long or short spacer groups (6 or 2 methylene units), the mesogenic groups orient preferably parallel to the polymer chains (axis of strain). The reason for this difference is not yet clear. These result…

Mechanical Properties of Composite SPEEK Polymer Membranes Modified with Ionic Liquids

2015

In this work, the mechanical properties of sulphonated polyetheretherketone (SPEEK) membranes impregnated with 3 different ionic liquids (1-butyl-2,3-dimethyl- imidazolium dimethylphosphate ([BMMIM][Me2PO4])), 1,2,3-trimethylimidazolium dimethylphosphate ([MMMIM][Me2PO4])), 1,3-dimethylimidazolium dimethylphosphate ([MMIM][Me2PO4])) have been investigated. Prepared SPEEK/ionic liquid composite membranes are characterized by mechanical testing both in room and elevated temperatures. It was found that the stiffness and tensile strength of composites decreased by increasing the content of ionic liquid and the length of alkyl radical in ionic liquid as well as by increasing the temperature.

Über die polymerisation von acrylsäurechlorid

1960

Monomeres Acrylsaurechlorid wird mittels Azodiisobuttersaurenitril in Dioxan bei 50°C polymerisiert. Bei Ausschlus von Feuchtigkeit und Sauerstoff entstehen bis zu 90% Umsatz unvernetzte Polymere. Durch Reaktion mit flussigem Ammoniak wurden Polyacrylamide erhalten, die zur viskosimetrischen Molgewichtsbestimmung dienten. Monomeric acrylyl chloride was polymerized in dioxane at 50°C by azo-bis-isobutyronitrile. With the exclusion of moisture and oxygen, a non-cross-linked polymer with a 90% yield was obtained. Polyacrylamides were formed by the reaction of polyacrylyl chloride with liquid ammonia. These products were used for viscosimetric molecular weight determinations.

Liquid crystal polymers (LCP) as processing aids and reinforcing agents. A study of nylon 6/LCP blends

1989

Influence de petites quantites d'un copolyesteramide thermotropique sur les proprietes mecaniques et la mise en œuvre du polyamide 6

ChemInform Abstract: Sustainable Carbon-Carbon Bond Formation Catalyzed by New Oxamate-Containing Palladium(II) Complexes in Ionic Liquids.

2014

New and versatile bis(oxamato)palladate(II) complexes (I) are synthesized and investigated for both Suzuki and Heck coupling reactions in molten tetra-n-butylammonium bromide as ionic liquid.

ChemInform Abstract: A Liquid-Liquid Biphasic Homogeneous Organocatalytic Aldol Protocol Based on the Use of a Silica Gel Bound Multilayered Ionic Li…

2012

Key feature of the title protocol is the use of a cis-ion-tagged proline dissolved in a liquid film on a multilayered ionic liquid covalently bound to silica. The resulting catalytically active material is soaked in cyclohexanone and water to form a semi-transparent gel which then reacts with the aldehyde.