Analytical Detectors Based on Microplasma Spectrometry

Miniaturizing all dimensions of apparatus, such as electronics and computers, is the current trend followed by scientists in various fields. The idea of Lab-on-a-Chip has significantly expanded and found its broad applications in analytical chemistry. Microplasmas can act as a sample excitation source and are the miniaturized versions of full-sized plasmas. These can be created in various forms, such as direct current, microwave induced, capacitively coupled and inductively coupled plasmas. Scaling down the size would reduce the amount of gases, liquids and consumables required, as well as the sample analysis time, which in turn would decrease the operating costs. Therefore, several research groups are involved in the development of microplasmas for utilisation in analytical instruments.     

磷化氢与环烯烃反应的原位^3^1P NMR研究

本文应用加压原位核磁共振波谱技术, 在反应温度50-70℃、反应压力1.0-2.0MPa, 氘代苯为溶剂, 偶氮二异丁腈为引发剂的条件下, 考察了磷化氢与环烯烃1, 5-环辛二烯、双环戊二烯、1, 3-环己二烯、1, 4-环己二烯及1, 5, 9-环十二三烯的反应。实验结果表明, 磷化氢与1, 5-环辛二烯反应主要生成双环膦杂环壬烷; 与其它环烯烃均不生成膦杂环化合物, 仅为一取代伯膦或二取代仲膦产物。磷化氢与环烯烃反应仍为串行机理。     

碱金属沸石上乙醇双分子缩合反应及其机理

首次发现在碱金属Ｘ沸石上乙醇能够发生以正丁醇为主产物的双分子缩合反应，在所研究的催化剂中，含Ｒｂ的ＬｉＸ沸石表现出较高的反应活性和选择性。反应机理的研究表明，反应不经过ａｌｄｏｌ缩合步骤。在此基础上，对反应机理提出了新建议：在碱性沸石作用下，乙醇的β－位Ｃ－Ｈ键被活化，双分子脱水导致缩合。碳链的增长按此模式进行。     

Indirect Determination of Captopril with Sodium Nitrate and Thiocyanate by Floatation Separation of Copper

A new method for indirect determination of captopril (CPT) with NaNO₃ and NH₄SCN by floatation and separation of copper has been studied. In the weak acid, a small amount of Cu(II) can be reduced to Cu(I) by CPT, then Cu(I) reacted with the SCN, which can float on the surface of the liquid phase with NaNO₃. A good linear relationship is observed between the floatation yield (E%) of Cu(II) and the amount of captopril. The linear range is 2?32 mg/L. On the ground, captopril can be indirectly determined by determining E(%) of Cu(II). The method is simple, rapid, reliable and has good selectivity. The developed method can be applied to indirect determination of captopril with satisfactory results.     

Gear-like array of (H_2O)_(12) as building blocks in one-dimensional supramolecular assembly

The preparation and crystal structure of complex Co(Hsae)_2·2H_2O (1,H_2sae=N-salicylidene-2-iminoethanol) are reported.X- ray analysis revealed that every six Co(Hsae)_2 forms a cyclic chip and every 12 water forms a novel gear-like cluster.Acting as building blocks,the gear-like water cluster and complex chip are connected in A-B fashion and extend into one-dimensional supramolecular chain.Hydrogen bond is the primary bridging force in the formation of supramolecular framework.     

Characterization of polystyrene and polyisoprene by normal-phase temperature gradient interaction chromatography

Temperature gradient interaction chromatography (TGIC) is applied to the characterization of polyisoprene (PI) and polystyrene (PS) using normal-phase (NP) stationary phase--bare silica or diol bonded silica. Tetrahydrofuran-isooctane mixtures are used as a mobile phase. PI and linear and star shaped PS samples are successfully fractionated in terms of the molecular mass with a high resolution comparable to that of reversed-phase (RP) HPLC. Temperature dependence of the retention shows that the enthalpy of adsorption of PS to the stationary phase is exothermic. In addition, some characteristic features of the NP-TGIC system relative to those of RP-TGIC are presented, which include a high sensitivity on the polar end group and the simultaneous size-exclusion chromatographic and TGIC characterization of PS and PI mixtures.     

Comparison of quantitative methods for analysis of polyphasic pharmaceuticals

Adequate very sensitive quantification methods are needed for the development and are also now required for the monitoring of undesirable solid form(s) as routine tests. The pre-requisite for quantitation are selectivity, sensitivity and most important the purity of standards and their proper storage, what is a challenge for metastable forms. Several analytical techniques are available such as X-ray diffraction, spectroscopy, thermal analysis and microcalorimetry. The different steps of the validation of the analytical methods and problems to be solved are discussed. Examples illustrate the different techniques and compare their possible advantages and limits. The relative standard deviation of measurements should allow for checking the homogenization procedure of mixtures for calibration. The validation should be carried out following ICH guidelines for validation of analytical methods. Comparison of different techniques in adequate concentration range add confidence in the analytical results.     

Ni-P/SiO_2催化剂晶化过程及其加氢活性研究

采用化学还原法制备了负载型Ni－P／SiO2非晶态合金催化剂．应用ICP、BET、氢氧滴定法、XRD、SEM、XPS研究了上述催化剂在高温晶化过程中的表面结构、表面形貌和表面电子态的变化。测定了Ni－P／SiO2非晶态合金晶化前后对其液相苯甲醛加氢反应催化活性和选择性,并讨论了非晶态合金催化剂晶化过程中结构变化对催化性能的影响．