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- Author or Editor: P. Wang x
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In order to assess the contribution of adenosine triphosphate and its metabolites to the cellular metabolism process in Saccharomyces cerevisiae, it is very important to simultaneously determine the relative concentrations of ATP and its metabolites. In this study, a fast, simple reversed-phase high-performance liquid chromatography with high selectivity was developed to simultaneously measure adenosine triphosphate and its metabolites (adenosine diphosphate, adenosine monophosphate, and cyclic adenosine monophosphate) in yeast. The method was performed under the gradient grogram, and the detection was monitored at 254 nm. Analysis was achieved within 25 min. The four components can be detected with linear response over the concentration range from 1 to 100 mg L−1 with excellent correlation coefficients (r 2) > 0.999. The recovery of the four analytes was 92.9%, 90.4%, 99.1%, and 105.1%, respectively. To demonstrate the good analysis of yeast samples, changes in the four adenine nucleotides levels caused by caloric restriction in yeast were determined. It is expected that the current method may contribute to further metabolomics and system biology investigations of yeast.
Abstract
The method of high-temperature hydrolysis separating fluorine from UF4 is described. The determination of the content of fluorine by different methods is performed and compared.
Abstract
Abstract
Hair samples from junior high school students in metropolitan areas of Taichung, Taiwan were tested for a total of 13 elements, Al, Ag, Br, Cl, Cr, Fe, K, La, Mn, Na, Sc, Se, and Zn by instrumental neutron activation analysis (INAA) to establish seasonal variations, gender and environmental exposures. The seasonal variations of hairs in 39 healthy students (18 males and 21 females; age 13.3 ± 0.4 years; height, 158.0 ± 4.1 cm; weight, 53.4 ± 5.7 kg) were collected at 1.5-month intervals for 1 year starting from late August, 2008. The concentrations of the above elements varied from 103 to 10−2 μg g−1 at different sampling times. A quantified index of agreement (AT) was introduced to help classify the elements. A smaller AT indicated highly consistent quantities of specific metals in the hair while a larger AT indicated increased fluctuation, i.e., less agreement. The different ATs in various hair samples were discussed. The concentrations of these elements are compared with the data in the literature.
Summary
A high-performance liquid chromatographic (HPLC) method coupled with photodiode array (PDA) detection has been developed and validated for simultaneous analysis of six active components (syringin, hyperoside, baicalin, quercetin, baicalein, and farrerol) of the Chinese medicinal preparation Qin-Bao-Hong antitussive tablet. The optimum conditions for separation were achieved on a 3.9 mm × 150 mm i.d., 5-μm particle, C18 column with a linear mobile phase gradient prepared from acetonitrile and 1% acetic acid at a flow rate of 1.0 mL min−1. Because of the different UV characteristics of these compounds, four detection wavelengths were used for the quantitative analysis (265 nm for syringin, 256 nm for hyperoside and quercetin, 277 nm for baicalin and baicalein, and 296 nm for farrerol). For all the analytes a good linear regression relationship (r > 0.999) was obtained between peak area and concentration over a relatively wide range. The method was validated for repeatability, precision, stability, accuracy, selectivity, and robustness. The validated method was successfully applied to simultaneous analysis of these active components in Qin-Bao-Hong antitussive tablet from different production batches.
Summary
A novel liquid-phase microextraction (LPME) technique, based on a hollow fiber (HF), in conjunction with high-performance liquid chromatography, has been developed for analysis of melamine in milk products. Melamine was extracted directly from milk products by use of a hollow-fiber membrane filled with organic solvent. HFLPME conditions, for example pH, extraction solvent, temperature, stirring rate, and extraction time were optimized. The best extraction efficiency of melamine was achieved under the conditions: pH 9.5, 35 μL n-octanol as extraction solvent, temperature 55°C, stirring rate 300 rpm, and extraction time 30 min. The HF-LPME technique resulted in a preconcentration ratio of 29-fold. Baseline chromatographic separation of melamine was achieved on a C18 column with 96:4 (v/v) 0.02 mol L−1 ammonium sulfate-methanol as isocratic mobile phase. The linearity of the method ranged from 1.0 to 100.0 μg mL−1, correlation coefficient 0.9994. The limit of detection by use of HF-LPME was 0.021 μg mL−1 at a signal-to-noise ratio of 3. The optimized HF-LPME technique was successfully applied to the analysis of melamine in milk products collected from different commodity manufacturing units.
Summary
A simple and rapid method, using online ultraperformance liquid chromatography with photodiode array detection and electrospray ionization mass spectrometry (UPLC-PDA-eλ-ESI-MS/MS), was developed for the in-depth analysis of 50 batches Radix et Rhizoma Rhei. The analysis was performed on a UPLC BEH C18 column using a gradient elution system. Baseline separation could be achieved in less than 7.5 min. At the same time, on the basis of the 50 batches of samples collected from representative cultivated regions, a novel chromatographic fingerprint was devised by UPLC-PDA, in which 27 common peaks were detected and identified by the developed UPLC-MS/MS method step by step according to fragmentation mechanisms, MS/MS data, standards, and relevant literature. Many active components gave prominent [M - H]− ions in the ESI mass spectra. These components include anthraquinones, sennosides, stilbenes, glucose gallates, naphthalenes, and catechins. Furthermore, based on the information of these Radix et Rhizoma Rhei components, and further combined with discriminant analysis, a novel discriminant analysis equation (DAE) was established for the quality control of Radix et Rhizoma Rhei for the first time.
Abstract
The thiourea complexes of antimony and bismuth triiodide were synthesized by a direct reaction of antimony and bismuth triiodide with thiourea powder at room temperature. The formula of the complex is MI3[SC(NH2)2]3(M=Sb, Bi). The crystal structure of the complexes belongs to monoclinic system and the lattice parameters are a=1.4772 nm, b=1.6582 nm, c=2.0674 nm and β=90.81 for SbI3(SC(NH2)2)3 and a=1.4009 nm, b=2.0170 nm, c=2.0397 nm and β=90.84 for BiI3[SC(NH2)2]3. The infrared spectra reveal that the trivalent antimony or bismuth ion is coordinated by the nitrogen atom, not the sulfur atom of the thiourea. Thermal analysis shows that there are two times structure rearrangements or phase transformation in the complexes from 100 to 170C.
Abstract
The aim of this paper is to consider using effective natural minerals in studying the retardation and migration of radium under the influence of groundwater in the far-field of a radioactive waste repository. The properties of adsorbing radium by minerals are studied by adopting the static and dynamic adsorption method. Preliminary experimental results give confidence in the validity of using Maifanshih and barite to adsorb radium in water and to serve as effective retarding materials in radioactive waste repositories, their Kd values being 3815 and 2955, respectively. The study on a certain number of conditions of adsorbing radium by the promissing material Maifanshih is reported for the first time. The mechanism of radium adsorption has been discussed and modeling of migration of radium in the minerals has been presented to establish a rational basis for the longterm prediction required for safety assessment of underground disposal of radioactive waste.
Abstract
Humic substances have attracted great interest in the investigation of metal ion behavior in the environment because of their special properties. Sorption and complexation of Pb2+ on MX-80 bentonite, LA bentonite, alumina and silica as a function of pH were studied in the presence and absence of fulvic acid (FA). The experiments were carried out in 0.01M and 0.001M NaNO3 solutions under ambient conditions. The results indicate that sorption of Pb2+ on the solid samples is strongly dependent on pH and FA. The sorption of Pb2+ is not influenced drastically by ionic strength. The nature of minerals/oxides, nature of humic substances and the composition of the solution are important factors in the behavior of metal ions in the environment. The results also indicate that FA has a positive effect on Pb2+ sorption at low and a negative effect at high pH values, and the results are discussed in the comparative complexation between FA-Pb2+ and Pb2+-minerals.
