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961.
The present paper describes stability indicating reverse phase high-performance liquid chromatography (RP-HPLC) assay method
for nitazoxanide in bulk drugs. The developed method is also applicable for the related substances determination in bulk drug.
The drug substance was subjected to stress conditions of hydrolysis, photolysis and thermal degradation. The considerable
degradation of nitazoxanide was observed under base and peroxide hydrolysis. The drug was found to be stable in other stress
conditions attempted. The chromatographic separation of the drug was achieved on reversed-phase C-18 column. Eluents were
monitored on photo-diode array detector at a wavelength of 240 nm. The mobile phase was aqueous 0.005 M tetra butyl ammonium
hydrogen sulphate and acetonitrile (45:55, v/v). In the developed HPLC method, resolution between nitazoxanide and its potential impurities, namely Imp-A (5-nitro-1,3-thiazol-2-amine),
Imp-B (N-(5-nitro-1,3-thiazol-2-yl) acetamide) and Imp-C (2-{[(5-nitro-1,3-thiazol-2-yl) amino] carbonyl} phenyl 2-(acetyloxy) benzoate)
was found greater than three. The developed RP-HPLC method was validated with respect to response function, accuracy, precision,
specificity, stability of analytical solutions and robustness. Also to determine related substances and assay determination
of nitazoxanide that can be used to evaluate the quality of regular production samples. The developed method can also be conveniently
used for the assay determination of nitazoxanide in pharmaceutical formulations. 相似文献
962.
本文利用溶胶-凝胶法在非水稀溶液中制备出SiO2包覆的ZnO量子点。通过紫外-可见吸收光谱(UV-Vis)和荧光光谱对合成量子点的发光特性进行了研究。结果表明,在nSiO2:nZnO=1∶4的条件下,ZnO量子点的发光性能最佳。经过Brus公式计算,该量子点的平均半径在2.8 nm左右,稳定性显著提高。其荧光光谱在363 nm处有一强而窄的激子发射峰,在519 nm处有一个宽而弱的绿色发射峰。说明SiO2对ZnO形成了有效包覆,明显减少了ZnO的表面缺陷。 相似文献
963.
Fatima Hassine Said Gmouh Mathieu Pucheault Michel Vaultier 《Monatshefte für Chemie / Chemical Monthly》2007,138(11):1167-1174
Summary. In this work was presented an application of the use of task specific onium salts (TSOSs) as soluble supports in Grieco’s multicomponent synthesis of tetrahydroquinolines. These soluble supports are of wide applicability and combine advantages
of solid phase synthesis without its limitations with those of solution phase chemistry. After a simple washing step, products
were cleaved from the supports and obtained in pure form and good yields. 相似文献
964.
对硫化铅固体表面的氯络合-溶解行为进行了研究。溶液化学计算考察颗粒表面固体反应产物(PbCl2)的生成与溶解情况表明,饱和氯化钠介质中PbCl2主要以[PbCl4]2-络合物的形式存在于溶液中,氯离子组分总浓度[Cl-]T=0·918mol/L时,PbCl2能较好地呈固态晶体析出,[Cl-]T>0·918mol/L时PbCl2晶粒因氯络合作用而溶解。通过Tafel实验进一步分析了PbS固体表面的腐蚀溶解行为,结果显示,当CFe3 ≤6×10-4mol/L时,腐蚀速度对Fe3 存在很强的依数性,浓度增加,腐蚀速度快速提高;CFe3 >6×10-4mol/L,有钝化现象发生。NaCl的加入,溶液相Cl-活度增加,PbCl2快速溶解,腐蚀反应加快。 相似文献
965.
H. Martin 《Angewandte Chemie (International ed. in English)》1966,5(1):78-84
Some recent examples of reactions proceeding both in the gas phase and in solution have been investigated to determine their kinetics and mechanisms. The ratio of the corresponding rate constants, kG and kL, of the elementary processes studied has been found to be about unity for unimolecular reactions and between 1 and 10 for bimolecular reactions. The mechanisms, overall rates, rate constants, and activation energies have been determined for the homogeneous gas reaction NOCl + Cl2O = NO2Cl + Cl2 and the reaction NOCl + N2O5 = NO2Cl + 2 NO2, carried out in C2F3Cl3. 相似文献
966.
The enthalpies of solution of NaRb[B4O5(OH)4]·4H2O in approximately 1 mol dm−3 aqueous hydrochloric acid and of RbCl in aqueous (hydrochloric acid + boric acid + sodium chloride) were determined. From these results and the enthalpy of solution of H3BO3 in approximately 1 mol dm−3 HCl(aq) and of sodium chloride in aqueous (hydrochloric acid + boric acid), the standard molar enthalpy of formation of −(5128.02 ± 1.94) kJ mol−1 for NaRb[B4O5(OH)4]·4H2O was obtained from the standard molar enthalpies of formation of NaCl(s), RbCl(s), H3BO3(s) and H2O(l). The standard molar entropy of formation of NaRb[B4O5(OH)4]·4H2O was calculated from the Gibbs free energy of formation of NaRb[B4O5(OH)4]·4H2O computed from a group contribution method. 相似文献
967.
A.S. Monayenkova A.A. Popova L.A. Tiphlova Y.V. Gorushkina A.V. Tsoi I.P. Romanova V.A. Alyoshin 《Thermochimica Acta》2005,430(1-2):83-86
The enthalpies of reactions between alkaline-earth cuprates M2CuO3 (M = Ca, Sr) and hydrochloric acid were measured in a hermetic swinging calorimeter at 298.15 K. The M2CuO3 samples were prepared by solid-phase synthesis from calcium or strontium carbonate and copper oxide and characterized by X-ray powder diffraction, EDX and wet analysis. The standard enthalpies of formation obtained for the cuprates, −1431 ± 4 kJ mol−1 for Ca2CuO3 and −1374 ± 3 kJ mol−1 for Sr2CuO3, are discussed and compared with previous experimental and assessed values. 相似文献
968.
A. Vadivel Murugan B. B. Kale Lalita B. Kunde Aarti V. Kulkarni 《Journal of Solid State Electrochemistry》2006,10(2):104-109
A comparative study of nanocrystalline spinel LiMn2O4 powders prepared by two different soft chemical routes such as solution and sol-gel methods using lithium and manganese acetates
are the precursors under different calcination temperatures. The dependence of the physicochemical properties of the spinel
LiMn2O4 powder has been extensively investigated by using thermal analysis (TGA/DTA), FTIR, X-ray diffraction studies, SEM, specific
surface area (BET) and electrical conductivity measurements. The results show that pure LiMn2O4 can be prepared from acetate precursors as starting materials at a low temperature of 600°C from solution route and 500°C
from sol-gel method. The charge-discharge characteristics and the cycling behavior of Li/1M LiBF4-EC/DEC electrolyte / LiMn2O4cells revealed that LiMn2O4 calcined at higher temperatures showed a high initial capacity, while the LiMn2O4calcined at lower temperatures exhibited a good cycling behavior. 相似文献
969.
0.8[xB2O3-(1 − x)SiO2]-0.2K2O (with 0 ≤ x ≤ 1) glasses were synthesized by melt quenching techniques. DSC curves of the glasses exhibit only one glass transition. Calorimetric measurements of heats of dissolution in lead borate at 973 K indicated small negative enthalpies of mixing. Consequently phase separation was not observed over the whole composition range. The results are in good agreement with the structural data available in the literature. 相似文献
970.
Two pure strontium borates SrB2O4·4H2O and SrB2O4 have been synthesized and characterized by means of chemical analysis and XRD, FT-IR, DTA-TG techniques. The molar enthalpies of solution of SrB2O4·4H2O and SrB2O4 in 1 mol dm−3 HCl(aq) were measured to be −(9.92 ± 0.20) kJ mol−1 and −(81.27 ± 0.30) kJ mol−1, respectively. The molar enthalpy of solution of Sr(OH)2·8H2O in (HCl + H3BO3)(aq) were determined to be −(51.69 ± 0.15) kJ mol−1. With the use of the enthalpy of solution of H3BO3 in 1 mol dm−3 HCl(aq), and the standard molar enthalpies of formation for Sr(OH)2·8H2O(s), H3BO3(s), and H2O(l), the standard molar enthalpies of formation of −(3253.1 ± 1.7) kJ mol−1 for SrB2O4·4H2O, and of −(2038.4 ± 1.7) kJ mol−1 for SrB2O4 were obtained. 相似文献