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21.
A new method for indirect determination of captopril (CPT) with NaNO3 and NH4SCN by floatation and separation of copper has been studied. In the weak acid, a small amount of Cu(II) can be reduced to Cu(I) by CPT, then Cu(I) reacted with the SCN, which can float on the surface of the liquid phase with NaNO3. A good linear relationship is observed between the floatation yield (E%) of Cu(II) and the amount of captopril. The linear range is 2?32 mg/L. On the ground, captopril can be indirectly determined by determining E(%) of Cu(II). The method is simple, rapid, reliable and has good selectivity. The developed method can be applied to indirect determination of captopril with satisfactory results. 相似文献
22.
StudiesonSystemsofLithiumandPotassiumHalidesfromSaltLakeandBitternResources(V)──TheQuaternaryReciprocalSystemLi ̄+,Br ̄-,I(-)-H... 相似文献
23.
Ammonium Chloro(thio)phosphate Betaines, a Class of Coordination-stabilized Chloro(thio)metaphosphates Ammonium chloro(thio)phosphate betaines behave like systems being in equilibrium with tert. amine and monomeric chloro(thio)metaphosphate. In solution at room temperature the amine component can be displaced by stronger donors. Mass spectra reveal the presence of ClPS2 as monomer and dimer, of ClPO2 by fragment ions of the dimer, trimer, and tetramer before reorganization takes place to form PXCl3 and P4X10 (X = O, S). Detection of ClPOS fails owing to fast equilibration into ClPO2 and ClPS2. 相似文献
24.
Preparation of Ammonium Rare Earth Halides totally free of Water Ammonium rare earth halides totally free of traces of water were prepared in an one step synthesis from metal, ammonium halide, and halogen in a two step temperature regime. 相似文献
25.
Farajollah?MohanazadehEmail author Mostafa?Hosini Mahmoud?Tajbakhsh 《Monatshefte für Chemie / Chemical Monthly》2005,136(12):2041-2043
Summary. Reduction of aldehydes and ketones to the corresponding alcohols was achieved in a simple procedure using the system sodium
borohydride and ammonium carbonate. This system needs lower excesses of reducing agent and leads to significantly shortened
reaction times. 相似文献
26.
A Setaram C-80 calorimeter has been modified in order to measure the heat flow of energetic materials at pressures up to 69 MPa. A manifold and sample cells capable of operating at high pressure were designed, constructed and evaluated. This paper will describe, in detail, the high pressure manifold construction, safety assessment and calibration. As well, the results for initial trials with ammonium nitrate (AN), and pentaerythritol tetranitrate (PETN) at various pressures and heating rates will be discussed. 相似文献
27.
Purification of plasmid DNA vectors by aqueous two-phase extraction and hydrophobic interaction chromatography 总被引:4,自引:0,他引:4
The current study explores the possibility of using a polyethyleneglycol(PEG)-ammonium sulphate aqueous two-phase system (ATPS) as an early step in a process for the purification of a model 6.1 kbp plasmid DNA (pDNA) vector. Neutralised alkaline lysates were fed directly to ATPS. Conditions were selected to direct pDNA towards the salt-rich bottom phase, so that this stream could be subsequently processed by hydrophobic interaction chromatography (HIC). Screening of the best conditions for ATPS extraction was performed using three PEG molecular weights (300, 400 and 600) and varying the tie-line length, phase volume ratio and lysate load. For a 20% (w/w) lysate load, the best results were obtained with PEG 600 using the shortest tie-line (38.16%, w/w). By further manipulating the system composition along this tie-line in order to obtain a top/bottom phase volume ratio of 9.3 (35%, w/w PEG 600, 6%, w/w NH4)2 SO4), it was possible to recover 100% of pDNA in the bottom phase with a three-fold increase in concentration. Further increase in the lysate load up to 40% (w/w) with this system resulted in a eight-fold increase in pDNA concentration, but with a yield loss of 15%. The ATPS extraction was integrated with HIC and the overall process compared with a previously defined process that uses sequential precipitations with iso-propanol and ammonium sulphate prior to HIC. Although the final yield is lower in the ATPS-based process the purity grade of the final pDNA product is higher. This shows that it is possible to substitute the time-consuming two-step precipitation procedure by a simple ATPS extraction. 相似文献
28.
A. I. Kazakov Yu. I. Rubtsov L. P. Andrienko G. B. Manelis 《Russian Chemical Bulletin》1998,47(3):379-385
The kinetic regularities of the heat release during the thermal decomposition of liquid NH4N(NO2)2 at 102.4–138.9 °C were studied. Kinetic data for decomposition of different forms of dinitramide and the influence of water
on the rate of decomposition of NH4N(NO2)2 show that the contributions of the decomposition of N(NO2)2
− and HN(NO2)2 to the initial decomposition rate of the reaction at temperatures about 100 °C are approximately equal. The decomposition
has an autocatalytic character. The analysis of the effect of additives of HNO3 solutions and the dependence of the autocatalytic reaction rate constant on the gas volume in the system shows that the self-acceleration
is due to an increase in the acidity of the NH4N(NO2)2 melt owing to the accumulation of HNO3 and the corresponding increase in the contribution of the HN(NO2)2 decomposition to the overall rate. The self-acceleration ceases due to the accumulation of NO3
− ions decreasing the equilibrium concentration of HN(NO2)2 in the melt.
For Part 2, see Ref. 1.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 395–401 March 1998. 相似文献
29.
Chenmou Zheng Xinmin Zhang Shan He Qun Fu Deming Lei 《Journal of solid state chemistry》2003,170(2):221-226
V2O3 nanopowder with spherical particles was prepared by reducing pyrolysis of the precursor, (NH4)5[(VO)6(CO3)4(OH)9]·10H2O, in H2 atmosphere. The thermolysis process of the precursor in a H2 flow was investigated by thermogravimetric analysis and differential thermal analysis. The results indicate that pure V2O3 forms at 620°C and crystallizes at 730°C. The effects of various reductive pyrolysis conditions on compositions of V2O3 products were studied. Scanning electron micrographs show that the particles of the V2O3 powder obtained at 650°C for 1 h are spherical about 30 nm in size with more homogeneous distribution. Experiments show that nanopowder has larger adsorption capacity to gases and is more easily reoxidized by air at room temperature than micropowder. Differential scanning calorimetry experiment indicates that the temperature of phase transition of nano-V2O3 powder is −119.5°C on cooling or −99.2°C on heating. The transition heats are −12.55 J g−1 on cooling and 11.42 J g−1 on heating, respectively. 相似文献
30.
A case study is presented for the establishment of traceability for ammonium nitrogen determination in wastewater in a routine laboratory in order to fulfil the requirements of ISO/IEC standard 17025. The necessary relevant information was obtained from the method validation data, the quality control data and equipment calibration certificates. The method of measurement is described together with the measurement equation, selected traceable reference standards and the associated measurement uncertainty. The major sources of uncertainty of the result of measurement were identified and the combined uncertainty was calculated. Identification of the main uncertainty sources represents the basis for target operations for reducing the measurement uncertainty of this determination. 相似文献