电化学分析在粘胶全硫量分析中的应用

采用电化学分析中的电导滴定法代替容量法和重量法,测定粘胶中的全硫量,具有快速、简便、准确的特点,能够满足生产控制分析的要求。

大蒜新素二烯丙基三硫化合物的化学分析

用氧瓶燃烧法 ,对合成得到的大蒜新素二烯丙基三硫化合物 (Ⅴ ) ,进行了元素硫定量分析 ,测定结果与HPLC方法数据基本一致 ,相对标准偏差为 0 .2 3%。

Quantitative Analysis Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Correlation between Mass Spectrometry Data and Sulfur Content of Crude Oils

Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) has become a powerful tool for analyzing the detailed composition of petroleum samples. However, the correlation between the numerous peaks obtained by FT-ICR MS and bulk properties of petroleum samples is still a challenge. In this study, the internal standard method was applied for the quantitative analysis of four straight-run vacuum gas oils(VGO) by atmospheric pressure photoionization(APPI) FT-ICR MS. The heteroatom class distribution of these VGO samples turned to be different when the concentration changed. Linear relationship between the normalized abundance and the concentration of VGO samples was identified for the total aromatic compounds, aromatic hydrocarbons, S1 and N1 species. The differences of the response factors were also discussed. The sulfur contents of a series of crude oils were proved to be linear with the FT-ICR MS data calibrated by the response factor of S1 species. This study demonstrated the feasibility of the internal standard method in quantitative analysis with APPI FT-ICR MS, and the bulk properties of petroleum samples could be correlated directly with the FT-ICR MS data.

Microanalysis and preliminary pharmacokinetic studies of a sulfated polysaccharide from Laminariajaponica

A rapid, sensitive and reproducible high performance liquid chromatography （HPLC） method with post-column fluorescence derivatization has been developed to determine the amount of low-molecular- weight sulfated polysaccharide （GFS） in vivo. The metabolism of GFS has been shown to fit a two component model following its administration by intravenous injection, and its pharmacokinetic parameters were determined to be as follows： half-time of distribution phase （t1/2α）=11.2±2.93 min, half-time of elimination phase （tl/2α）=98.20±25.78 min, maximum concentration （Cmax）=110.53 gg/mL and peak time （Tmax）=5 min. The pharmacokinetic behavior of GFS was also investigated following intragastric administration. However, the concentration of GFS found in serum was too low for detection, and GFS could only be detected for up to 2 h after intragastric administration （200 mg/kg body weight）. Thus, the bioavailability of GFS was low following intragastric administration because of the metabolism of GFS. In conclusion, HPLC with post-column derivatization could be used for quantitative microanalysis and pharmacokinetic studies to determine the presence of polysaccharides in the serum following intravenous injection.

Thermogravimetric Study and Modeling of Direct Sulfation of Limestone by Sulfur Dioxide

The direct sulfation of limestone from different sources in Iran was studiedin a thermogravimetric analyzer under atmospheric pressure. All limestone samples tested have higherthan 97% CaCO_3. Experimental conditions were as follows: particle size levels ranging from 1.6 μmto 7.8 μm, four level reaction temperatures (700℃, 750℃, 800℃ and 850℃), and two SO_2concentrations (2.4 x 10^(-3) and 3.2 x 10^(-3) mol · mol^(-1)). The particle size and temperatureshowed dominant influences on the rate and level of conversion while the effect of SO_2concentration was weak. The shrinking core model can be used to describe the behavior of thesulfation process. The reaction kinetics and diffusion mechanism are both important in controllingthe rate of the process. The two key parameters of the model, chemical rate constant K_s andeffective diffusion coefficient D_(eff) were obtained. Model predictions are in good agreement withthe experimental data.

Electron Momentum Spectroscopy of Ethanethiol Complete Valence Shell

The binding energy spectra and electron momentum distributions for the complete valence orbitals of ethanethiol were measured for the first time by binary （e, 2e） electron momentum spectroscopy employing non-coplanar symmetric kinematics at an impact energy of 1200 eV plus binding energy. The experimental results are generally consistent with the theoretical calculations using density functional theory and Hartree-Fock methods with various basis sets. A possible satellite line at 17.8 eV in binding energy spectrum was observed and studied by electron momentum spectroscopy.

Sulfur poisoning mechanism of three way catalytic converter and its grey relational analysis

Combining a detailed catalytic surface reaction mechanism with noble metal and promoter elementary reactions, a new three-way catalytic converter(TWC) reaction mechanism is established. Based on the new mechanism, steady condition numerical simulation is carried out, and the change of light-off temperatures and conversion efficiency with various SO2 contents is obtained. By grey relational analysis(GRA), the relational grade between conversion efficiency and SO2 content is obtained. And, the result shows that SO2 content has the most important influence on C3H6 and NOX conversion efficiency. This provides an important reference to the improvement of activity design of TWC, and may provide guidance for the condition design and optimization of TWC.

A new distance correction method for sulfur analysis in coal using online XRF measurement system

When X-ray fluorescence （XRF） technology is used to measure the sulfur concentration in coal online, the measurement accu- racy is affected by the coal＇s uneven surface and the particle size. In order to improve the accuracy of sulfur concentration measurement, an online measurement system, consisting of a portable X-ray fluorescence instrument and an auxiliary distance correction module, was developed in this paper. By measuring the standard coal samples of known sulfur concentration, we obtained a calibration curve that can be used to analyze the sulfur concentration. We studied the relationship between the X-ray fluorescence intensity （I） and the distance （D） from surfaces to instrument. The results showed that there was a good linear re- lationship between 1 and D when the sulfur content was certain. Based on these knowledge, the distance correction formula of X-ray fluorescence intensity was proposed. By applying the distance correction formula to experimental sulfur concentration measurement, we demonstrated that the measurement accuracy can be significantly increased.