Search results for "Potassium"
showing 10 items of 930 documents
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
Thermal studies of sulphonamide derivative complexes
1991
Abstract A thermal study of a new series of acetazolamidate complexes of Co(II), Ni(II) and Cu(II) using the TG, DTG and DTA techniques in flowing air, static air and N 2 atmospheres is described. From the TG-DTG and DTA curves, different thermal behaviours can be observed. Although in all the complexes the processes of dehydration, deammination and pyrolysis can be clearly observed, in some cases they appear as several well-separated steps and, in others, as continuous stages which take place simultaneously. The differences observed between the pyrolytic decomposition in flowing air and in nitrogen are described. In flowing air, metal sulphate is formed from the thiadiazole ring, except fo…
The influence of the cation on the conformation of the anion μ-hydridobis[pentacarbonylchromium(0)]: crystal and molecular structure of [(phenH)2Cl][…
1999
Abstract The crystal and molecular structures of [(phenH)2Cl][Cr2(CO)10(μ-H)] (1) and [K(phen)2][Cr2(CO)10(μ-H)] (2) have been determined by single crystal X-ray diffraction. The availability of the potassium cation for the carbonyl oxygens coordination influences the conformation of the anion in 2 as demonstrated by the comparison with the non-coordinating [(phenH)2Cl] cation in 1 and with literature data.
Behaviour of the non-linear optical material KTiOPO4in the temperature range 293-973 K studied by x-ray diffractometry at high resolution: alkaline d…
1999
The crystal structure of potassium titanyl phosphate, KTiOPO4 (space group Pna21), has been refined at room temperature, at 673 K, and at 973 K, by using accurate single-crystal x-ray diffraction techniques at high resolution (dmin = 0.35 A). The data show a large amount of anharmonic motion of the potassium ions, increasing with temperature. To describe this motion, two models are developed: a normal refinement including potassium anharmonic thermal displacement parameters, which describes the average motion of the alkaline sites, and another model in which the potassium sites are split within the harmonic approximation and the displacements of the potassium ions versus temperature are des…
ATR-FTIR and XRD quantification of solid mixtures using the asymptotic constant ratio (ACR) methods. Application to geological samples of sodium and …
2019
Two asymptotic constant ratio methods applied to the quantification of individual components of solid samples using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) are described. The methods involve the measurement of the peak current/peak areas of selected signals (diffraction peaks in XRD and absorption bands in ATR-FTIR) relative to the signal of standard added in constant proportion to the sample and the sample enriched with the analyte following the usual standard additions methodology. The proposed method compensates the absorption effects appearing in XRD and the presence of overlapping absorption bands of interferents by me…