Authors:W.-Y. Liu, X.-J. Yang, P. Li, F. Feng, and L.-Sh. Mao
10-O-(N,N-dimethylaminoethyl)-ginkgolide B (XQ-1) is an intermediate for synthesizing 10-O-(N,N-dimethylaminoethyl)-ginkgolide B methanesulfonate (XQ-1H), which is a novel ginkgolide B derivative and is being developed as a platelet-activating factor antagonist. A specific and rapid liquid chromatographic method was developed for the quantitative analysis of XQ-1 and its three related impurities, which were 10-O-(N,N-dimethylaminoethyl)-11,12-seco-ginkgolide B (imp-1), 10-O-(N,N-dimethylaminoethyl)-11,12-seco-3,14-dehydroginkgolide B (imp-2) and 10-O-(N,N-dimethylaminoethyl)-3,14-dehydroginkgolide B (imp-3) simultaneously in XQ-1 samples. Chromatographic separation was achieved on a CN band stationary phase, with the mobile phase consisting of methanol and 20 mM dipotassium hydrogen phosphate (pH 7.5) (50:50, υ/υ) in isocratic elution. The flow rate was 1.0 mL min−1 and detector was set at 220 nm. The method was optimized by the analysis of the samples generated during the forced degradation studies. The XQ-1, imp-1, imp-2, and imp-3 were completely separated within 15 min. The resolutions (Rs) amongst four target compounds were >2. The developed method was validated with respect to specificity, linearity, accuracy, precision, and robustness. The results indicated that the simultaneous LC determination method was readily utilized as a quality control method for XQ-1 sample.
Authors:L. Li, Q. Wang, Y. Yang, G. Wu, X. Xin, and H. A. Aisa
The chemical compositions of essential oils extracted by n-hexane extract (HE), petroleum ether extract (PE), dichloromethane extract (DE), and hydrodistillation (HD) from Carthamus tinctorius L. (safflower) were analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 86 compounds from four different extracts were identified, and the contents were 97.65%, 98.05%, 98.93%, and 99.68%, respectively. 6,10,14-Trimethyl-2-pentadecanone, hexadecanoic acid, methyl ester, hexadecanoic acid, 8,11-octadecadienoic acid, methyl ester, and 9,12,15-octadecatrien-1-ol were the major constituents of the extracts. The antidiabete activity was assayed in vitro by against protein tyrosine phosphatase 1B (PTP1B). The results showed that the HE exhibited the best in vitro inhibitory enzyme activity against PTP1B, which holds a good potential for treating diabetes and obesity.
Authors:X. Li, J. Xu, Y. Jiang, L. Chen, Y. Xu, and C. Pan
High-performance liquid chromatography with a hydrophilic-interaction liquid chromatographic (HILIC) column has been successfully used to retain and separate the polar phosphonic herbicides glyphosate and glufosinate. Online electrospray tandem ion-trap mass spectrometric and DAD detection were used. The effects on the separation of mobile phase acetonitrile content, buffer concentration, and flow rate, and of column temperature, were investigated. With UV-visible detection at 195 nm, LOQ were <850 mg kg−1, showing the method is suitable for product quality control of these herbicides alone or in combination. Tandem mass spectrometric conditions were optimized for ion-trap detection. Quantification was by use of selected reaction monitoring transitions m/z 168 → 150 in negative-ion mode for glyphosate and m/z 182 → 136 in positive-ion mode for glufosinate. Limits of detection (LOD; S/N > 3) were 0.20 and 0.16 ng for glyphosate and glufosinate, respectively, and the respective limits of quantification (LOQ; S/N = 10) were 0.02 and 0.05 mg kg−1. Sample derivatization was not necessary to achieve low detection limits in residue analysis in this study. Recovery from watermelon, spinach, potato, tomato, radish-root, and water fortified with the herbicides ranged from 63.6 to 107.3% and relative standard deviations were <15.3%.
Authors:Z. Wang, M. Lv, D. Li, Z. Zhou, L. Zhang, and W. Yang
A new HPLC method has been established for determination of 3-monoiodotyrosine (MIT), 3,5-diiodotyrosine (DIT), 3,5-diiodothyronine (T2), 3,3′,5-triiodothyronine (T3), 3,3′,5′-triiodothyronine (rT3), and thyroxine (T4) produced by hydrolysis of iodinated casein with barium hydroxide. The hydrolytic stability of each analyte was evaluated. Iodinated casein was hydrolyzed with saturated barium hydroxide solution for 16 h at 110°C and the barium ions were then removed as barium sulfate. Reversed-phase HPLC was performed on a 2.1 mm × 150 mm, 5 μm particle, C18 column with a mixture of acetonitrile and 0.1% (v/v) formic acid as mobile phase at a flow rate of 0.2 mL min–1. Acetonitrile was maintained at 5% (v/v) for 5 min and then increased linearly to 50% (v/v) within 35 min. All analytes were quantified by measuring the absorbance at 280 nm. Validation data indicated the method was linear, with regression coefficients (R2) > 0.998, in the concentration ranges investigated. Sensitivity was adequate—limits of detection (LOD) were 0.04–0.38 μg mL–1 and limits of quantification (LOQ) were 0.05–0.38 μg mL–1. Accuracy and precision were acceptable — for all the analytes recovery was 82.0–93.0% and repeatability, as relative standard deviation, was 1.0–3.0%. Hydrolytic stability tests indicated MIT and DIT are much more stable than the other analytes. rT3 was not released directly from iodinated casein but was formed by deiodination of T4 during hydrolysis. The method could be used to identify iodinated casein, to evaluate its activity and quality, and for supervision and regulation of feed additives.
Authors:L. Fu, Y. Chen, H. Du, J. Mao, X. Shi, and S. Li
A novel double -diketone 1,6-bis(1-phenyl-3-methyl-5-oxo-pyrazol-4-yl) hexanedione-[1,6] (BPMOPH) was further studied on its coordination compounds with uranium and thorium, respectively. The IR, UV, and1H-NMR spectra were examined, and the proposed structure is discussed.
Authors:H. Ye, N. Ren, H. Li, J. Zhang, S. Sun, and L. Tian
The complex of [Nd(BA)3bipy]2 (BA = benzoic acid; bipy = 2,2′-bipyridine) has been synthesized and characterized by elemental analysis, IR spectra, single
crystal X-ray diffraction, and TG/DTG techniques. The crystal is monoclinic with space group P2(1)/n. The two–eight coordinated Nd3+ ions are linked together by four bridged BA ligands and each Nd3+ ion is further bonded to one chelated bidentate BA ligand and one 2,2′-bipyridine molecule. The thermal decomposition process
of the title complex was discussed by TG/DTG and IR techniques. The non-isothermal kinetics was investigated by using double
equal-double step method. The kinetic equation for the first stage can be expressed as dα/dt = A exp(−E/RT)(1 − α). The thermodynamic parameters (ΔH≠, ΔG≠, and ΔS≠) and kinetic parameters (activation energy E and pre-exponential factor A) were also calculated.
Authors:X. He, Z. Zhang, L. Feng, Z. Li, J. Yang, Y. Zhao, and Z. Chai
After an acute exposure to lanthanum chloride, the pharmacokinetics of calcium uptake in rats was studied by radioactive 47Ca tracer. The accumulated doses of calcium in the left femurs during 24 hours were determined. The results showed that the
area under the curves (AUC), specific activity of maximal blood 47Ca concentration (Cmax), distribution rate constant (Ka) and the accumulated dose of calcium in the left femur decreased while time to Cmax (Tpeak) increased with the rising dosage of lanthanum exposure. It indicated that lanthanum expose had a negative effect on calcium
Authors:K. Ito, H.-L. Li, Y. Saito, T. Yamamoto, Y. Nishihara, Y. Ujihira, and K. Nomura
The size distribution of free-volume (<~0.1 nm3) of ethylene-vinyl alcohol copolymer with various crystalline degrees was estimated by positronium lifetime measurement. With increasing degree of crystallinity, the size distribution significantly narrowed and the intensity of positronium decreased. This indicates that the inhomogeneity reduces with the increase of the degree of crystallinity. It is found that the free-volume fraction estimated is reflected by the fraction of the amorphous region.
Authors:Z. Zhang, F. Li, L. Xu, N. Liu, H. Xiao, and Z. Chai
Chemical behavior of lanthanum in root tips excized from wheat seedlings growing at both promotional and inhibitory levels of LaCl3 in culture solutions was investigated by a sequential leaching procedure combined with instrumental neutron activation analysis. The results indicate that most of La exists in non-exchangeable species and the binding of La3+ to the root tips is extremely stable. The root tips during growing at the inhibitory level of LaCl3 absorb much more La than those at the promotional level. However, the La proportion in each fraction is similar for both groups.