用傅里叶变换红外光谱法研究聚对苯二甲酸乙二酯的结构

用傅里叶变换红外光谱法,将一系列不同温度下退火的PET光谱与熔融淬火的PET光谱进行数字吸光度相减,得到不同结晶状态的“反式构象光谱”。进一步将不同温度退火的“反式构象光谱”(240℃和120℃)彼此相减,可得到“纯晶区的光谱”和“非晶区的反式构象光谱”。通过差示光谱的比较,发现一些新的谱带和谱带的变化。可用PET 的晶区和非晶区中其分子链的内旋转构象的变化解释。     

反相薄层色谱应用的探索

近年来,薄层色谱(TLC)技术已发展成为一种重要的分析手段。由于它所需要的设备、条件简单,造价低廉,检出灵敏度高,分离效果好,用样少而且不破坏样品,操作方便、快速,因此容易建立和推广。 薄层色谱是利用混合物中各组分的物理化学性质的差异,使各组分在固定相和流动相中的分配系数(或吸附平衡常数)不同,引起各组分迁移速度的差异而得到分离。正     

聚二乙烯苯多孔微球液相色谱性能的研究

本文是在研究成孔性与孔结构的基础上进一步探讨高交联度聚二乙烯苯多孔微球在色谱过程中的吸附和溶解对保留的贡献。实验证明,无论在极性或非极性淋洗剂条件下、许多种有机化合物在分离过程中均以溶解的贡献为主;因此认为研究淋洗剂的改性对高分子固定相选择性的影响较与对硅胶类固定相更富有实际意义。实验中并建立了评价高分子本体对色谱峰展宽贡献的方法。最后介绍了在择优条件下得到的液相色谱应用实例。     

微型高效液体色谱分离芳烃

微型高效液体色谱(Micro High Performa-nce Liquid Chromatography)简写 MHPLC,是近年来高效液体色谱(简写 HPLC)发展中一个值得注意的动向,在77年底才有公开文献发     

STUDY OF DEPENDENCE OF LIQUID CHROMATOGRAPHIC PERFORMANCE UPON PORE STRUCTURE OF POROUS POLYDIVINYLBENZENE MICROSPHERES

Pore structure of the porous polydivinylbenzene microspheres is controlled by the degreeof crosslinkage and the diluent used. It is proved by chromatographic results that the higher thedegree of crosslinkage is, the more the micellar pores will be formed, and the nature as wellas the quantity of the diluent determine the real pore structure. Among the structural para-meters of the microspheres, the size and the pore diameter affect the performance in HPLCmostly. The linear sample capacity of the microspheres in 1--2 order of magnitude larger thanthat of the Silica-ODS. According to this result, it could be confirmed that the solute mole-cules penetrate deeply into the skeleton of the polymer network. Based on the polymeric struc-ture with the same chemical composition but different in pore structure, the contribution tothe retention of several organic compounds by Henry's and/or adsorption coefficient has beenstudied. The results obtained show that Henry's coefficient is approximately 80% of thetotal contribution, i. e. dissolution mechanism plays the main role in the chromatographicprocess, especially in case of polar compounds. The experimental result that the chroma-tographic separation relatively slightly depends upon the sueface area of the polymer isanother ovidence. It is better to define this kind of polymeric stationary phase as a sorbentrather than an adsorbent. From the point of view of dissolution mechanism, it is suggestedthat a homogeneous porous polymeric stationary phase constructed with chemically rigid ske-letal structure and sufficiently thin bulk polymeric phase inside the microspheres should bean ideal packing for chromatography.     

微型液相色谱柱行为的研究——柱长、柱效和流动相对分离的影响

前言通常应用的液相色谱柱的柱径为4mm,柱长为15～30cm;近年来的趋势是采用更短的色谱柱(柱长为5～10cm)以及更细的柱径(φ0.5～1mm)。这种短而细的色谱柱的优点很明显:短柱的柱压远低于长柱,降低了对高压的要求,相应地降低了仪器的造价;此外,采用短柱,也使分离时间缩短,有利于快速分析。细径柱的优点是流动相耗费量少,0.5mm的柱子所消耗的流动相仅为常规4mm柱的1/100左右。但更短的微型柱的应用却很少报导。     

聚二乙烯苯多孔微球孔结构和液相色谱性能的研究

聚二乙烯苯多孔微球的孔结构受控于交联度及稀释剂,从色谱方法证明交联度高对形成微束孔有利,而稀释剂的质和量则决定真孔的性质。微球的结构参数中以微球的尺寸及孔径对高效液相色谱性能影响较大。微球的试样线性容量比十八烷基硅氧烷键合硅胶大1—2个数量级,说明溶质分子是扩散进入到高分子骨架中的。文中以化学组成相同、孔结构不同的聚二乙烯苯微球为基础,研究了溶解及吸附对几种有机化合物的保留值的贡献,对极性溶质来说,溶解系数约占总贡献的80％。从许多实验结果也说明此类固定相的比表面对色谱的分离度贡献不大。因此称此种固定相为吸着剂较称之为吸附剂更好。可以设想,具有刚性骨架的高分子组成、高分子本体相又足够薄的均匀多孔微球将是一种较理想的固定相。