流动注射比浊法测定人体体液中钾

基于四苯硼钠与钾作用产生浊度 ,探讨并优化了流动注射分析条件 ,从而建立了测定人体体液中钾的新方法。方法简便、快速 ,每小时进样 6 0次 ,线性范围为 1.0× 10 - 4～ 1.0× 10 - 3mmol·ml- 1,所测尿样和血样的相对标准偏差分别为 3.0 8%和 2 .6 3%。     

The contribution of the pressure drop to analyte retention in coupled column supercritical fluid chromatography of lipids

Summary This paper reports the qualitative and quantitative effects of the column pressure drop on the retention of lipid components in a serially coupled capillary column SFC system. The contribution of the pressure drop consists of two components, the density effect and the flow effect. The magnitude of the flow effect,i. e. the change in retention which results from changes in the flow-rate when column pressures are changed, is determined by the difference in single column analyte k values. The effect will be positive compared with the uncorrected retention values when the column with largest k value is closest to the injector. With the columns in reversed order, the effect will be negative. The contribution from the density effect always resulted in larger coupled column k values and was in most instances of more significance than the flow effect component. Values calculated with and without pressure drop correction have been compared and it has been shown that for most of the eighteen model lipid compounds investigated, the deviations from the experimental retention factors were smaller when pressure drop corrections were made.     

Supercritical fluid chromatography of industrial paraffins and waxes

Summary The application of capillary SFC for SIMDIST investigations of paraffins and waxes is reported. Pressure, density and temperature of the mobile phase are optimized to obtain high chromatographic resolution of complex mixtures of industrial products. Isothermal linear pressure programming and asymptotic pressure and density programming are used in the range from 15 to 35 MPa in the isothermic mode above 100°C. SFC chromatograms of natural and synthetic paraffins, microcrystalline wax and candle wax are compared. The retention behaviour of paraffin mixtures and waxes has been investigated on methyl/phenyl and biphenyl capillary columns. The polarity of the stationary phases influences the absolute retention time more than it influences the chromatographic resolution.     

催化裂化USY／ZnO／Al2O3脱硫添加剂的高温水热失活

 对USY／ZnO／Al2O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察，发现老化后添加剂的脱硫性能大幅度下降．采用XRD和IR等技术对USY／ZnO／Al2O3添加剂在高温和高温水热条件下失活的原因进行了研究．结果表明，在高温下，ZnO可与USY沸石中的铝发生固相反应生成ZnAl2O4尖晶石，从而造成USY晶体结构崩塌，转变成无定形状态．在ZnO含量较高的条件下，ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应，生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构．这一方面使添加剂失去了可形成硫化物吸附中心的ZnO，另一方面破坏了硫化物的裂化活性组分USY，从而造成添加剂脱硫性能下降甚至失去脱硫活性．ZnO对USY的破坏作用主要与温度有关．在USY／ZnO／Al2O3体系中，ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离，单纯的高温条件对添加剂的破坏不显著，而水蒸气可以促进ZnO的移动，有利于ZnO与USY的接触，因此在高温和有水蒸气存 在的条件下添加剂的结构易遭到破坏．     

Headspace single-drop microextration for the detection of organotin compounds

The performance of single-drop microextraction (SDME), coupled with gas chromatography/mass spectrometry, was assessed for the determination of tributyltin compounds in water and solid samples. Experimental parameters impacting the performance of SDME, such as microextraction solvent and sampling and stirring time, were investigated. Analytical results obtained by SDME were compared with those generated by conventional solid phase microextraction (SPME) and liquid-liquid extraction (LLE) for the determination of TBT in PACS-2 sediment certified reference material (CRM).     

醌类化合物的超临界流体萃取研究进展

综述了国内近20年来超临界流体萃取技术应用于醌类化合物分离的研究进展,重点介绍了超临界流体萃取技术在中草药中醌类化合物的分析测定方面的应用,分析了影响醌类成分提取效果的主要因素,优化萃取温度和萃取压力能够改善琨类化合物的分离效果,夹带剂的使用则有效地提高了超临界流体的萃取能力。     

Solubility of α-amino acids in water under high pressure: glycine, -alanine, -valine, -leucine, and -isoleucine

The solubility of glycine, -alanine, -valine, -leucine, and -isoleucine in water was measured at 298.15 K and pressures up to 400 MPa. The standard deviation of the logarithm of the solubility is 0.001–0.003, equal to or better than the accuracy of atmospheric pressure measurement in the literature (0.001–0.05). A variety of solubility phenomena were observed. The solubility of glycine decreased with increasing pressure, whereas that of -alanine increased. The -valine and -isoleucine have a solubility maximum at around 100 MPa, and -leucine seems to exhibit a solid-phase phase transition at around 200 MPa. Pressure coefficient of the solubilities at 0.10 MPa is compared with that thermodynamically estimated in reference to aqueous density measurements of glycine and -alanine at 298.15 K and 0.10 MPa, supporting a reliability of our high-pressure measurements.     

Fe／ZrO_2气凝胶超细粒子催化剂的制备、表征及F－T反应性能的研究

用超临界流体干燥法制备出大孔高比表面高分散态Ｆｅ／ＺｒＯ_２气凝胶超细粒子催化剂，研究了在其制备过程中织构性质、颗粒大小、体相和表面结构的变化，并与普通浸渍法制备的Ｆｅ／ＺｒＯ_２催化剂作了对比。对几种Ｆｅ／ＺｒＯ_２催化剂的Ｆ－Ｔ反应性能考察表明，Ｆｅ／ＺｅＯ_２气凝胶超细催化剂显示出高的反应活性；随载体ＺｒＯ_２颗粒尺寸减小，活性组分铁的分散度变大，其颗粒尺寸变小，催化剂比表面积增大，反应活性增大，甲烷和低碳烃生成量增加，重质组分减少，认为产物烃分布主要受催化剂活性相颗粒尺寸效应制约。     

Some solvable models of nonuniform classical fluids

A model classical fluid is constructed by assuming that the direct correlation functionc(r – r) is independent of any applied external field. Thermodynamic consistency requires thatc(r – r) 0, and permits explicit representation of the model by a many-body interaction potential. In the canonical ensemble, the model shows a phase transition to an infinite density condensed phase, but in the grand canonical ensemble only an anomalous transition to zero density vapor is found to stably exist.