A high-performance liquid chromatography (HPLC) method has been developed for simultaneous determination of six alkaloids, i.e., (−)-(R)-platydesmin, noroxyhydrastinine, berberine, skimmianine, canthin-6-one, and pteleine in the herbal medicine of Phellodendron amurense Rupr. The optimal condition for extraction and separation was achieved with a linear mobile phase gradient prepared from 0.1% phosphoric acid and acetonitrile. The LODs and LOQs for the analytes ranged from 0.06 to 0.22 μg mL−1 and from 0.25 to 0.80 μg mL−1, respectively. The optimized method was applied to the determination of alkaloids in P. amurense Rupr. and was found to be efficient. This method can provide a scientific and technical platform to the manufacturers for setting up a quality control standard as well as to the public for quality and safety assurance of the proprietary traditional Chinese medicines.
Authors:D.-Y. Yang, Q.-X. Liu, X.-L. Xie, and F.-D. Zeng
The exfoliated poly(vinyl chloride) (PVC)/montmorillonite
(MMT) nanocomposites were synthesized by in situ intercalated polymerization
of vinyl chloride (VC) in the presence of organic-intercalated montmorillonite
(OMMT). Their structures and thermal properties were characterized. The results
showed that layered silicates are well exfoliated and uniformly distributed
in PVC matrix during in situ intercalated polymerization of VC in the presence
of OMMT. The glass transition temperatures of PVC phases in the PVC/MMT nanocomposites
are all lower than that of pristine PVC due to the incorporation of the exfoliated
silicate layers in PVC matrix. The 5% mass loss temperature (T5%),
the dehydrochlorination temperature (Tmax1)
of the PVC matrix decreased due to the free and interlayer water in MMT, the
low thermal stability, and the enhanced dehydrochlorination of the PVC matrix
by alkyl ammonium pre-treated MMT. However, the thermal decomposition temperature
of the dehydrochlorinated PVC (Tmax2)
and char at 600C are slightly increased in the presence of silicate layers.
Authors:B. Zhou, S. Jiang, L. Zou, X. Wang, D. Wang, J. Liu, S. Shang, and D. Zhou
A new compound cyclohexyl-t-butyldimethylammonium tetraphenylborate, [C6H11N(CH3)2(C(CH3)3)]BPh4 has been prepared, and its decomposition mechanism was studied by TG. The IR spectra of the products of thermal decomposition were examined at every stage. Kinetic analysis for the first stage of thermal decomposition process was obtained by TG and DTG curves, and kinetic parameters were obtained from the analysis of the TG-DTG curves with integral and differential equations. The most probable kinetic function was suggested by comparison of kinetic parameters.
Authors:Z. Xiao, D. Liu, C. Wang, Z. Cao, X. Zhan, Z. Yin, Q. Chen, H. Liu, F. Xu, and L. Sun
The effect of mechanical alloying on Zn-Sb alloy system is investigated with X-ray diffraction (XRD), laser grain size analysis
and differential scanning calorimetry (DSC) respectively. The results of laser particle size analysis shows that the particle
size decreases with increasing of the grinding time between 0 and 24 h. XRD and DSC results indicate that longer the grinding
time of Zn-Sb is, the more content of Zn4Sb3 become in the product in this process.
Authors:H. Bai, X. Jin, F. Wang, J. Du, Y. Liu, and D. Chen
The preparation of a cold kit was introduced in the paper, and the effective quantities of the components (Vc, HEDP and SnCl2·2H2O) in the kit were determined. At the sametime, the effects of labelling kit on the reaction time, reaction temperature and animal distribution were studied in detail. The initial animal experiment showed the high uptake in the skeletal tissue, the clearance in the blood was quick.
Authors:Y. P. Liu, Y. Y. Di, W. Y. Dan, and D. H. He
Bis(1-octylammonium) tetrachlorocuprate (1-C8H17NH3)2CuCl4(s) was synthesized by the method of liquid phase reaction. The crystal structure of the compound has been determined by X-ray crystallography. The lattice potential energy was obtained from the crystallographic data. Molar enthalpies of dissolution of (1-C8H17NH3)2CuCl4(s) at various molalities were measured at 298.15 K in the double-distilled water by means of an isoperibol solution-reaction calorimeter, respectively. In terms of Pitzer's electrolyte solution theory, the molar enthalpy of dissolution of (1-C8H17NH3)2CuCl4(s) at infinite dilution was determined to be and the sums of Pitzer's parameters and were obtained.
Authors:W. Liu, F. Chaspoul, D. Berge Lefranc, L. Decome, and P. Gallice
Occupational exposure to Cr(VI) causes various effects including deep skin ulcerations. Its action mechanisms are not fully
understood. In the present study, the evaluation of human dermal fibroblasts heat production was monitored, using microcalorimetry.
as part of Cr(VI) toxicity. In control cells, normal heat production was 15±5 pW/cell. Regardless of the Cr(VI) concentration
tested (0 to 500 μM), heat production was inhibited over time periods ranging from 3 to 25 h. These results could be correlated
with cell mortality and the IC50 for Cr(VI) was 29±4 μM. In the WST-1 bioassay, the IC50 was 35±5 μM (no statistical difference). Thus, Cr(VI) altered the metabolism of the fibroblasts, and led to cellular death.
Microcalorimetry can be a useful tool for determining the toxic effect of suspect compounds implicated in the occurrence of
Authors:Z. Ren, W. Liu, Y. Hou, Y. Zhu, L. Chang, and D. Ma
Thermogravimetry (TG) was employed to study the thermal degradation kinetics of poly(etherketone/sulfone)ethylimide (PEK-IE and PES-IE). The corresponding decomposition activation energies and reaction orders were obtained and the comparison was made with their parent polymerspoly(ether-ketone/sulfone) with Cardo group (PEK-C and PES-C). The results show that the degradation activation energies of PEK-IE and PES-IE were lower than that of PEK-C and PES-C; and two stages of the degradation process were found for all the four polymers. For PEK-IE and PES-IE, the activation energies in the first decomposition stage are much lower than that in the second stage and the two stages can be taken as slow induction and fast degradation, whereas for PEK-C and PES-C the activation energies in the first decomposition stage are larger than that in the second stage, and the two stages can both be taken as two fast degradation stages. The decomposition mechanism of the two stages was also speculated.
Authors:Yuan-Fang Liu, Cheng Luo, K. Moody, D. Lee, G. Seaborg, and H. Von Gunten
Two procedures are described for fast separations of berkelium from complex mixtures of reaction products arising from heavy
ion reactions, such as18O+248Cm. The first procedure uses a combination of several extraction steps with a final separation on a cation exchanger, the
second procedure starts with an anion exchange column which is followed by multiple extractions in different media. The elements
separated in the different steps were analyzed and overall decontamination factors are given.
Authors:W. Zhou, X. Y. Zhang, Y. P. Lv, X. D. Liu, C. Xu, and G. L. Duan
Radix Isatidis has widely useful activities including anti-virus, anti-bacterial. Tryptanthrin, indigo, and indirubin are active ingredients in R. Isatidis. Response surface methodology (RSM)-optimized infrared-assisted extraction (IRAE) was developed and combined with HPLC for simultaneous determination of tryptanthrin, indigo, and indirubin from R. Isatidis. IRAE were investigated through extraction yields of the three components and optimized by RSM. The optimum conditions were as follows: infrared power of 129 W, solid/liquid ratio of 1:40 g/mL, and irradiation time of 22.5 min. IRAE conditions obtained by RSM were not only accurate, but also had practical value reflecting the expected optimization. Subsequently, this novel IRAE method was evaluated by extraction yield of the components of R. Isatidis samples from different regions. Compared with common extraction methods including maceration extraction (ME), reflux extraction (RE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), IRAE showed higher yield with advantages of no limitation of solvent selection, low cost, convenience under optimum extraction conditions. These results suggested the potential of RSM-optimized IRAE for extraction and analysis of the water-/fat-soluble compositions of Chinese herbal medicine. A simple chromatographic separation for simultaneous determination of tryptanthrin, indigo, and indirubin from Chinese herbal medicine R. Isatidis was performed on a C18 column (Diamonsil 150 mm × 4.6 mm i.d., 5 μm) with a mobile phase isocratic consisting of methanol and water at a flow-rate of 0.8 mL min−1. The retention times of tryptanthrin, indigo, and indirubin were 15.4, 31.9, and 58.6 min, respectively. The linear equations were obtained as follows: y = −3094.5744 + 21208.792x for tryptanthrin (R = 0.9998, 0.9–18.0 μg mL−1), y = 4730.0448 + 30180.567x for indigo (R = 0.9997, 0.5–10.0 μg mL−1) and y = −6582.9045 + 67069.312x for indirubin (R = 0.9997, 0.4–8.0 μg mL−1). The result showed that RSM-optimized IRAE was a simple, efficient pretreatment method for the analysis of complex matrix.