Search results for "otas"
showing 10 items of 1136 documents
eta1-Allypalladium complexes with tridentate PNP’ ligand for the assembly of modified Screen Printed Electrodes: an electrochemical study.
2015
Specific Pd-based organometallic complex, in particular the [Pd(η1-CH2–CH=CH2)(P–N–P’)]BF4 was used for the assembly of chemically modified Screen Printed Electrodes (SPEs) and their electrochemical reactivity was also investigated. For this purpose potassium ferricyanide, hexaammineruthenium(III) chloride, sodium hexachloroiridate-(III) hydrate, ascorbic acid (AA), uric acid (UA), acetaminophen (Ac), guanine (G) and adenine (A) were used to study the electron-transfer processes, which occurred at modified SPEs, fabricated by using the [Pd(η1-CH2–CH=CH2)(P–N–P’)]BF4, applying the drop casting procedure. Interesting results were obtained in the case of the guanine (G) quantitative detection,…
Flow injection flame atomic spectrometric determination of iron, calcium, magnesium, sodium and potassium in ceramic materials by using a variable-vo…
1993
A series of different ceramic materials, such as porcelain, feldspar, kaolin, varnish, clay and stoneware have been analyzed. Iron, calcium and magnesium have been determined in these materials by flame atomic absorption and sodium and potassium by flame emission. The use of a variable-volume injector enables one to carry out these analyses in a flow system (after fusion of samples with lithium metaborate) and does not require different dilutions for the determination of each type of sample considered, nor the use of different flow injection manifolds. The developed procedure provides a limit of detection of 100 μg/l for Na, 70 μg/l for Ca, 50 μg/l for both Fe and K and 8 μg/l for Mg. The c…
Atomic-absorption spectrometric determination of calcium, magnesium and potassium in leaf samples after decomposition with molten sodium hydroxide
1991
Abstract The decomposition of standard leaf samples of varied origin and nature by fusion with sodium hydroxide in an open system has been studied. The use of sodium nitrate as an auxiliary agent facilitated the mineralization of most of the samples. The solutions obtained were analysed for calcium, magnesium and potassium by flame atomic-absorption spectrometry. The method is fast and quite precise, with absolute standard deviations of 0.04–0.13, 0.002-0.03 and 0.04–0.12% for calcium, magnesium and potassium contents of O.8-5.0, 0.13–0.48 and 0.36–2.2% respectively. The limits of detection (μg/ml) in the determination step were 0.10 for calcium, 0.011 for magnesium, and 0.09 for potassium.
Automated determination of reboxetine by high-performance liquid chromatography with column-switching and ultraviolet detection.
2000
A fully automated method including column-switching and isocratic high-performance liquid chromatography (HPLC) was developed for quantitative analysis of the new antidepressant reboxetine, a noradrenaline reuptake inhibitor. After serum injection into the HPLC system and on-line sample clean-up on a silica C8 (10x4.0 mm I.D.) clean-up column with an eluent consisting of 2.5% acetonitrile in deionized water, the chromatographic separation was performed on an analytical column (Lichrospher CN; 250x4.6 mm I.D.) with an eluent of acetonitrile-aqueous potassium phosphate buffer (0.008 M, pH 6.4) (50:50). The UV detector was set at 273 or 226 nm. The limit of quantification was about 15 ng/ml at…
Photo-induced chemiluminescence determination of the pesticide Buminafos by a Multicommutation flow-analysis assembly
2008
Abstract The preliminary experiments in this paper deal with the photo-induced chemiluminescent behaviour of Buminafos family, after the experimental screening tests and several of them resulted positive, the herbicide Buminafos was selected to develop a new analytical method. The determination of Buminafos was performed with the aid of a Multicommutation (a solenoid valve set) assembly. The method involves the on-line photo-degradation of the analyte (stopped flow, 5 s) with the selected suitable medium (0.05% hydrogen peroxide) and its subsequent chemiluminescent oxidation by the potassium permanganate. Sample solution alternated segments with the photo-degradation medium; and, after the …
Automated determination of amisulpride by liquid chromatography with column switching and spectrophotometric detection.
2003
A fully automated chromatographic method including on-line blood serum or plasma clean-up, isocratic high-performance liquid chromatography (HPLC) and spectrophotometric detection was developed for quantitative analysis of the new antipsychotic drug amisulpride. After injection of serum or plasma onto the HPLC system and clean-up on a pre-column (10x4.0 mm I.D.) filled with Silica CN 20 micrometer (pore size 10 nm) by an eluent consisting of 8% acetonitrile in deionized water, the chromatographic separation was performed on Lichrospher CN (5 micrometer; 250x4.6 mm I.D.) by an eluent consisting of 50% acetonitrile and 50% aqueous potassium phosphate buffer (0.008 M, pH 6.4). The UV detector …
Direct FIA—AS determination of potassium and magnesium in cement samples by use of the slurries approach
1992
A direct procedure has been developed for the flame atomic determination of potassium and magnesium in cement samples. A 50-mg sample is dispersed in 25 ml of 0.13M nitric acid; 100 mul of this slurry is injected in a double channel FIA manifold simultaneously with 100 mul of a 10% (w/v) lanthanum solution. This procedure allows the rapid extraction of potassium and magnesium by leaching of the sample; nitric acid is not necessary if only potassium must be determined and the sample can be diluted with only distilled water. Aqueous standards are used. The manifold employed includes a well-stirred mixing chamber, which provides an adequate on-line dilution of the sample, in order to obtain em…
On-line bi-directional electrostacking for As speciation/preconcentration using electrothermal atomic absorption spectrometry.
2006
A method using bi-directional electrostacking (BDES) in a flow system is presented for As preconcentration and speciation analysis. Some parameters such as electrostacking time and applied voltage, support buffers and their concentrations were investigated. Boric acid plus sodium hydroxide at 0.1mol/l concentration was selected as support buffer to improve the pre-concentration factor (PF) for As(V). An analytical range from 2.0 to 50.0mugl(-1), and 0.35mugl(-1) as limit of detection, when applied 750V for 20min, were achieved. Under these conditions, a pre-concentration factor of 4.8 was obtained. The proposed method was applied to determine As(V) in mineral water and natural water samples…
Mechanical and electrophysiological effects of cromakalim on the human urinary bladder.
1994
The effects of cromakalim on spontaneous and induced mechanical activity of human detrusor muscle were investigated in vitro. Cromakalim produces a concentration-related decrease of spontaneous as well as carbachol- and K(+)-evoked contractions. This is the first study to utilize the patch clamp technique to elucidate the mechanism of action of cromakalim on human detrusor cells. Cromakalim hyperpolarizes the detrusor cells by increasing the net outward current which is most likely carried by potassium ions. In the human urinary bladder, this effect is mediated by a glibenclamide-sensitive potassium channel, as glibenclamide is able to diminish the relaxant effect of cromakalim and to preve…
CCDC 238449: Experimental Crystal Structure Determination
2005
Related Article: Ming-Liang Tong, M.Monfort, J.M.C.Juan, Xiao-Ming Chen, Xian-He Bu, M.Ohba, S.Kitagawa|2005|Chem.Commun.||233|doi:10.1039/b415431b