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991.
the ethylenediamine/pyridine-2-carbaldehyde/copper(I) system is used in a new spectrophotometric method for the determination of ethylenediamine. The batch procedure involves the formation of an orange chelate between the Schiff's base and copper(I) ions at pH 8.5 (borate buffer) and measurement of the absorbances at 475 nm against water after 10/2-15 min; Beer's law is obeyed over the range 0.5/2-11.2 μg ml?1 and the molar absorptivity is 6.21 × 103 l mol?1 cm?1. Tolerance limits for different amines [36] and other organic compounds [12] are reported. In the optimized flow-injection system, ethylenediamine (1.4/2-84.6 μg ml?1 is determined at a sample throughput of 55 h?1. The method is sensitive and selective and is satisfactory for the determination of the diamine in aminophylline and pharmaceutical preparations (ethylenediamine contents from 0.031 to 3.23%) with relative errors ranging from ?7.4 to +11.1% and relative standard deviations of about 0.65% for both procedures. 相似文献
992.
Speciation of inorganic selenium using hydride generation method is a widespread analytical method nowadays. However, a reduction step of Se(VI) to Se(IV) is necessary as the hydride-forming species is HSeO(3)(-) (oxydation state+IV). This paper describes the development of a batch assisted microwave system allowing a rapid (<5 min) conversion of Se(VI) to Se(IV). Hydride generation is performed by a flow injection system and detection by ICP/MS. Detection limits of 6 and 8 pg for Se(IV) and for Se(VI) (by using a sample loop of 200 mul) respectively have been achieved. This method has been validated by participating in a European certification exercise for inorganic Se speciation in aqueous solutions. 相似文献
993.
P. Y. Mu X. L. Jiang J. Chen J. C. Wang Qiange He Y. J. Zhu M. J. Jin Fang Li 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(3):669-671
Research on extracted 90Y with di(2-ethylhexyl) orthophosphoric acid (P204) in lipiodol for liver cancer was made to evaluate the stability of extracted
90Y with P204 in lipiodol (90Y-P204-lipiodol) in serum of newly-born cattle and human’s blood. At first, P204 (extractant) was dissolved in lipiodol (organic
phase). Secondly, 90Y was extracted to organic phase after adding 90Y solution into test tube with P204 and lipiodol in it. The extracting efficiency with 0.01 mol/l P204 could reach 99.4%.
The stability of 90Y-P204-lipiodol has been experimented in physiological saline solution as preparation for further stability experiment. The
result indicated that the extracted 90Y lost 0.02%–0.36% in physiological saline solution. The results of further stability experiment showed that loss efficiencies
of extracted 90Y after adding newly-born cattle serum 1 hour, 1 day, 3 and 7 days are 3.38%, 3.12%, 4.29% and 6.62%, respectively, and loss
efficiencies of extracted 90Y after adding human’s blood 1 hour, 1 day, 3 and 7 days are 2.55%, 5.91%, 7.88% and 5.63%, respectively. Our data also indicated
that 90Y is the most possible radioisotope for being extracted with P204 in lipiodol to treat hepatocellular carcinoma, particularly
in cases of unresectable liver tumors, since 90Y is available from several commercial sources in clinical quality. We conclude that the stability of 90Y-P204-lipiodol tested with newly-born cattle serum and human’s blood attained great results. 90Y-P204-lipiodol is a kind of potential and exciting pharmaceutical in inerventional therapy for liver cancer and we can carry
on the further animal test and clinical trial. 相似文献
994.
An optical immunosensor based on surface plasmon resonance (SPR) has been developed for immunosensing. The sensor is designed on the basis of fixing incident angle of light and measuring the reflected intensities in the wavelength range of 400-800 nm simultaneously. The SPR spectrum was shown in terms of reflected light intensities versus wavelengths of incident light. The intensity of the reflected light reaches the minimum at the resonant wavelength. Molecular self-assembling in solution is used to form the sensing membrane on gold substrate. The kinetic processes of sensing monolayer formation were studied. The basic fibroblast growth factor, a kind of basic polypeptide, was determined in the concentration range of 0.24-9.6 μg/ml. Under optimum experimental conditions, the sensor has a good repeatability, reversibility and selectivity. 相似文献
995.
Tayagaki T Galet A Molnar G Muñoz MC Zwick A Tanaka K Real JA Bousseksou A 《The journal of physical chemistry. B》2005,109(31):14859-14867
The 1A1 left arrow over right arrow 5T2 spin transition has been investigated in the solid solutions of Fe(x)M(1-x)(pyrazine)[Pt(CN)4] (M = Ni or Co, 0 < or = x < or = 1) having a three-dimensional polynuclear structure. Both Ni and Co dilutions tend to decrease the hysteresis width and smooth the transition curves. The enthalpy (entropy) change associated with the spin transition was found to decrease from 26 kJ mol(-1) (84 J K(-1) mol(-1)) for x = 1 to 12 kJ mol(-1) (47 J K(-1) mol(-1)) for 47% Co dilution and to 15 kJ mol(-1) (54 J K(-1) mol(-1)) for 59% Ni dilution. Raman spectroscopy revealed a mixed one- and two-mode behavior in the solid solutions. For the first time, a correlation between vibrational frequencies exhibiting one-mode behavior and the entropy change, which drives the spin crossover, is established. 相似文献
996.
Muñoz J Barril X Hernández B Orozco M Luque FJ 《Journal of computational chemistry》2002,23(5):554-563
A similarity index based on the hydrophilic/hydrophobic properties of molecules is presented. Such an index is defined based on the fractional partition of the free energy of solvation developed within the framework of the self-consistent reaction field MST model, which divides the free energy of solvation or the free energy of transfer into contributions assigned to the surface elements defining the solute/solvent interface. These surface contributions can be integrated to derive atomic or group contributions. The suitability of the index to compute the molecular similarity based on hydrophobic/hydrophilic properties is examined by considering their application in a variety of test systems, including structure-activity relationships, absorption properties, and molecular recognition. The similarity index is expected to be a very powerful tool in molecular similarity studies for compounds of chemical, biochemical, and pharmaceutical interest. 相似文献
997.
环糊精衍生物气相色谱手性毛细管柱的制备与考察 总被引:5,自引:0,他引:5
合成了3种新的含长烷基链的β-环糊精衍生物手性固定相。实验表明,随着烷基链长的增加,对手性卤代烃和酯的立体选择性有所提高;以OV-7为手性固定相的稀释剂对多数手性化合物的拆分效果好于OV-1701。2,6-O-二辛基-3-O三氟乙酰-β-环糊精/OV-7柱应用于不对称合成及催化中对映体的分离与测定和白酒中乳酸乙酯对映体含量的测定。 相似文献
998.
Using unnatural amino acid mutagenesis, the binding site for serotonin at the novel Caenorhabditis elegans receptor MOD-1 has been probed. As with the closely related serotonin receptor 5-HT3, MOD-1 makes use of a strong cation-pi interaction between the ammonium of serotonin and the indole side chain of a tryptophan. However, the specific Trp used by MOD-1 is different from that used for 5-HT3 (and the nAChR), aligning with a residue more than 40 amino acids distant in sequence space and on a different "loop" of the agonist binding site. This suggests a significant rearrangement of the ligand on binding these two closely related receptors. It is suggested that, unlike enzymes, receptors and other signaling molecules may need only to deliver an agonist to a general binding region, rather than establishing precise drug-receptor interactions. 相似文献
999.
In this article, equilibrium and kinetics of the ligand exchange reaction between a series of N,N-disubstituted dithiocarhamate chelates of Nickel (Ⅱ) have been studied by means of high-performance liquid chromatography in various solvents such as chloroform, dichloromethane, methylbenzene, ethyl acetate and DMF (dimethyl formamide) etc. at 30 ℃. The activation parameters of two selected reactions with different disubstituted alkyl groups have been determined in toluene. The experimental results indicate that steric effect of the alkyl groups may influence to some extent the rate of ligand exchange. The reactions of ligand exchange conform to an S_N2 mechanism. Statistical factor seems to enter the evaluation of the equilibrium constants. Solvation effect may contribute to the influence of solvents on reaction rate. 相似文献
1000.
Chuan-xiang Chen Shao-lin Mu Department of Chemistry School of Sciences Yangzhou University Yangzhou China 《高分子科学》2002,(4):309-316
Polyphenol film deposited on platinum foil can continuously grow with time during the electrolysis of a phenolsolution consisting of 0. 1 mol L~(-1) phenol, 3 mol L~(-1) NaOH and 0.5 mol L~(-1) Na_2SO_4, as has been proved by the methods ofsweep potential, constant potential and constant current, and visible spectra during the electrolysis of phenol. A polyphenolfilm with thickness of 0.11 mm was obtained by the electrolysis of phenol at a constant potential of 0.70 V (versus Ag/AClwith saturated KCl solution). Polyphenol film is inactive and stable in 2 mol L~(-1) H_2SO_4 solution, neutral solution and3 mol L~(-1) NaOH solution and in the potential range between -0.95 and 1.35 V. The usable potential range is dependent onthe pH value. Polyphenol has an ESR signal with a g factor of 2.0049. The conductivity of polyphenol is 1.2×10~(-4) S cm~(-1). Inthe solution of polyphenol dissolved in DMSO, the mobility of polyphenol anions is 8×10~(-9) m~2 s~(-1) V~(-1) at 20℃. 相似文献