Group-type analysis of gasoline range materials by high performance liquid chromatography

Hydrocarbon group-type analysis of gasoline-range materials is a very important method for evaluating feedstocks and products in the petroleum industry. In this paper the method of group-type analysis of gasoline-range materials by high performance liquid chromatography is investigated. The results demonstrte that the separation of saturates and olefins can be accomplished with reactivated and cooled columns. The low-temperature columns and the use of n-hexane as an eluent play a particularly important role in the improvement of the separation.     

高效液相色谱法对二氢吡喃酮衍生物的手性拆分

介绍了利用手性chiralcel OD和chiralpak AD柱在高效液相色谱上对一系列二氢吡喃酮衍生物进行手性拆分，获得了良好的分离结果，考察了部分对映体在这两种柱上的色谱行为。实验表明手性化合物与手性柱之间存在着化学作用与空间作用，两者的共同作用决定了分离结果。     

免疫法制备液相色谱生物样品的研究——血中沙丁胺醇的分析

用动物免疫法制备了免疫亲和柱纯化水溶性的沙丁胺醇血浆样品。琥珀酸酐交联沙丁胺醇和牛血清白蛋白获得抗原免疫家兔抗沙丁胺醇抗体——免疫球蛋白。琼脂糖Ｓｅｐｈａｒｏｓｅ４Ｂ与抗体交联制成免疫球蛋白亲和柱。对高效液相色谱法测定中的一般提取方法和固相小柱提取法作了比较，后者具有内源性杂质干扰少的优点，是生物样品预处理的一种有效的方法     

Miniaturization of solid-phase reactors for on-line post-column derivatization in narrow-bore liquid chromatography

Summary The use of solid-phase reactors for post-column derivatization in narrow-bore HPLC (1.0mm i.d. analytical columns) is evaluated. Two systems are described, viz. for the determination of N-methylcarbamate pesticides and for that of urea and ammonia. The solid-phase reactor is packed with a strong anion exchange resin and urease immobilized on silica, respectively, to effect the catalytic hydrolysis of the solutes eluting from the analytical column. In both systems, the hydrolysis product is reacted with o-phthalaldehyde followed by fluorescence monitoring. Analytical data are presented and band broadening from various parts of the reaction detector system is discussed. An on-line trace enrichment procedure via a micro precolumn is descried for the trace level determination of N-methylcaramates in surface water samples.     

气相法分析化妆品中的防腐剂

 采用大口径中极性毛细管柱HP 170 1(15m× 0 5 3mmi d × 1 0 μm)对苯甲醇、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯和对羟基苯甲酸丁酯等化妆品中常用的 5种防腐剂进行了气相分析方法研究。结果表明 ,该毛细管柱能够很好地分离这 5种化合物 ,抗干扰性良好 ,其检出限分别是 13ng ,70ng ,70ng ,10 0ng和 10 0ng ,线性范围为 5 0ng～ 5 0 0ng。     

On the stability of micro-LC columns (packed fused silica capillary columns)

The life expectancy and resistance to flow, pressure shocks, solvent gradients, and bending of packed fused silica capillary columns (Micro-LC) are discussed.     

基于钢筋低周疲劳的桥墩地震易损性分析

基于Coffin-Manson钢筋疲劳损伤模型,采用非线性纤维梁柱单元,对纵筋采用HRB335和HRB500E的圆柱形桥墩拟静力试验进行数值模拟,研究拟静力作用下低周疲劳对钢筋和构件承载力退化的影响.为了进一步研究钢筋低周疲劳对试件累积损伤的影响,将Takemura和Kunnath提出的两组不同加载模式下的拟静力试验进行数值模拟.结果表明:基于Coffin-Manson模型,采用纤维单元,在材料层面上考虑钢筋的低周疲劳,可以较好地模拟试件在不同加载模式下的累积损伤和承载力退化.     

The destabilizing effect of external damping: Singular flutter boundary for the Pflüger column with vanishing external dissipation

Elastic structures loaded by non-conservative positional forces are prone to instabilities induced by dissipation: it is well-known that internal viscous damping destabilizes the marginally stable Ziegler's pendulum and Pflüger column (of which the Beck's column is a special case), two structures loaded by a tangential follower force. The result is the so-called ‘destabilization paradox’, where the critical force for flutter instability decreases by an order of magnitude when the coefficient of internal damping becomes infinitesimally small. Until now external damping, such as that related to air drag, is believed to provide only a stabilizing effect, as one would intuitively expect. Contrary to this belief, it will be shown that the effect of external damping is qualitatively the same as the effect of internal damping, yielding a pronounced destabilization paradox. Previous results relative to destabilization by external damping of the Ziegler's and Pflüger's elastic structures are corrected in a definitive way leading to a new understanding of the destabilizating role played by viscous terms.     

The efficient synthesis of carbon–carbon double bonds via Knoevenagel condensation using red mud packed in a column

Abstract

Red mud (RM) is generated as a by-product during the production of alumina from bauxite ore. In this study, RM packing in a column is used as a catalyst for carbon–carbon double bond formation via Knoevenagel condensation. The reactants are added to the top of the column and then eluted with solvent. The products are collected in high yields and short time. RM packed in a column eliminates a catalyst separation step from the reaction mixture in this work.     

液相色谱测定土壤中4种硝基苯胺类化合物

建立了索氏提取-液相色谱-紫外检测器(SE-HPLC-UV vis)测定土壤中4种硝基苯胺同系物的方法。在以Hypersil BDS C18为色谱柱,55%甲醇为流动相,流速1 mL/min,检测波长230 nm时,4种物质可以在10 min内实现良好分离。对于索氏提取,本研究指出,采用二氯甲烷作为提取剂,能极大地消除HPLC-UV vis检测中的背景干扰。在单因素实验的基础上,得出最佳的提取条件如下:温度55℃,时间8h,提取剂用量60 mL。方法回收率>90%,RSD在1.9%～4.1%之间。