Authors:Yang-Xi Yu, Qing-Yin Zhang, and Guang-Hua Gao
In order to predict extraction equilibria for uranyl nitrate and nitric acid between aqueous and tributyl phosphate (TBP)-hydrocarbon diluent solutions, activity coefficient equations for the three components in the system HNO3-UO2(NO3)2-H2O were derived and the general equation for excess Gibbs energy, proposed by Clegg and Pitzer, simplified. The activity coefficient equations comprise a Debye-Hückel term and a Margules expansion carried out to the four suffix level, where the higher order electrostatic contribution was neglected. The binary parameter was determined from the thermodynamic properties of the two relevant aqueous solutions. The three mixing parameters were obtained by correlating data for the partial pressure of nitric acid over HNO3-UO2(NO3)2-H2O solutions at 298.15 K. By using the mixing parameters, the activity coefficients of the ternary system can be calculated with good accuracy, and the solubility of uranyl nitrate in aqueous nitric acid with concentration up to 14 mol/kg can be satisfactorily predicted.
Authors:Lahu Yang, Hua Yin, Wehua Zhu, and Suhua Niu
Thermal behaviour of codeine phosphate and codeine crystallized at the several solvents system was studied by DSC, and then,
the kinetic parameters and thermochemical data have been obtained. We have found that codeine phosphate and codeine exist
in a number of polymorphic formes which may inflicence the bio-availability.
Authors:Yang-Xin Yu, Tie-Zhu Bao, Guang-Hua Gao, and Yi-Gui Li
In order to obtain the exact information of atomic number density in the ternary system of HNO3−UO2(NO3)2−H2O, the densities were measured with an Anton-Paar DMA60/602 digital density meter thermostated at 298.15±0.01 K. The apparent
molal volumes for the systems were calculated from the experimental data. The present measured apparent molar volumes have
been fitted to the Pitzer ion-interaction model, which provides an adequate representation of the experimental data for mixed
aqueous electrolyte solutions up to 6.2 mol/kg ionic strength. This fit yields θV, and ψV, which are the first derivatives with respect to pressure of the mixing interaction parameters for the excess free energy.
With the mixing parameters θV, and ψV, the densities and apparent molar volumes of the ternary system studied in this work can be calculated with good accuracy,
as shown by the standard deviations.
Authors:H. Yang, Hua Yin, Z. Wang, L. Fan, Q. Li, and X. Zhu
Traditional Chinese medicine (TCM) has been widely used in many countries for thousands of years and played an indispensable role in the prevention and treatment of diseases, especially the complicated and chronic ones. However, the application of TCM in diseases is still not fully recognized by people around the world, the main reason is that Chinese herb is a very complex mixture containing hundreds of different components. Thus, it is essential to make quality control and evaluation of TCM. A new quality evaluation method, quantitative analysis of multi-components by single marker (QAMS), was developed to the quality control of alkaloids in TCM, a case study on Radix aconiti lateralis, named Fuzi in Chinese. Six alkaloids, including aconitine, hypaconitine, mesaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine, were selected as main components to evaluate the quality of Radix aconiti lateralis. The feasibility and accuracy of QAMS were checked by the external standard method, and various high-performance liquid chromatographic instruments and chromatographic conditions were investigated to verify its applicability. Using aconitine as the internal reference substance and the content of aconitine was calculated according to relative correction factors by high-performance liquid chromatography. The present results showed that there was no significant difference observed between the QAMS method and the external standard method with the relative average deviations less than 3.0%, and QAMS is an effective way to control the quality of herbal medicines and seems to be a convenient and accurate approach to analyze multi-composition when reference substances are unavailable.
A high-performance liquid chromatography—diode-array detection method was developed and validated to determine simultaneously eleven major alkaloids in Corydalis decumbens (Thunb.) Pers. The alkaloids detected were corlumidine, protopine, coptisine, tetrahydrojatrorrhizine, palmatine, berberine, sanguinarine, papaverine hydrochloride, tetrahydropalmatine, bicuculline, and corydaline. Chromatographic separation was achieved using a C-18 column with a mobile phase composed of A (0.2% acetic acid solution, adjusted with triethylamine to pH 5.0) and B (acetonitrile), with stepwise gradient elution. Ultraviolet diode-array detection was used; chromatograms were examined at the wavelength of 280 nm. The regression equations showed a good linear relationship between the peak area of each marker and concentration (r = 0.9994–0.9999). The recovery values ranged between 93.66% and 100.54%. The method was fully validated with respect to detection and quantification limits, precision, reproducibility, and accuracy. The described high-performance liquid chromatography (HPLC) method was successfully used for the differentiation and quantification of the eleven major alkaloids in C. decumbens (Thunb.) Pers. and can be considered an effective procedure for the analyses of this important class of natural compounds.
Authors:Hua Shao, Jing-Tian Han, Guo-Xin Sun, Bo-Rong Bao, Yong-Hui Yang, and Si-Xiu Sun
The extraction performance of uranium(VI) from nitric acid with N-octanoylpiperidine (OPPD) in series of diluents has been investigated. The dependence of extraction distribution on the concentrations of aqueous nitric acid and OPPD and also the temperature has been studied. The experimental results showed that the decreasing order of extraction ability of OPPD is as follows: benzene, dimethyl benzene (DMB), toluene, 1,2-dichloroethene, n-octane, carbon tetrachloride, cyclohexane, chloroform. It cannot be interpreted only on the basis of polarity of the diluents. The interaction between extractant or extracted species and diluent is discussed.