Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry, Ernst-Moritz-Arndt-University of Greifswald, Greifswald, Germany.
J Sep Sci. 2010 Oct;33(19):2930-42. doi: 10.1002/jssc.201000281.
Calixarene-bonded stationary phases received growing interest in HPLC as stationary phases with special retention characteristics and selectivity. The commercially available unsubstituted and p-tert-butyl-substituted Caltrex(®) columns have been intensively studied and characterized in our workgroup. They can be used as reversed phases, yet they support additional interactions. Especially, their steric, polar and ionic properties differ from conventional alkyl-bonded phases. However, also the hydrophobic interaction shows differences since adsorption and partition interactions on or in a bonded layer of calixarenes are not similar to those of alkyl-bonded layers. The relative strength of the hydrophobic properties of the stationary phases has been found depending on the methanol concentration of the mobile phase. Generally, the dependencies of their interaction strengths on mobile-phase conditions, e.g. the change of the intensity of the hydrogen-bonding abilities with decreasing methanol content, are not similar from phase to phase either. This probably gives calixarene-bonded stationary phases enhanced suitability for analyses at extreme compositions of the mobile phase. An overview about the synthesis, retention and selectivity properties of Caltrex(®) columns is given here.
冠醚键合固定相作为具有特殊保留特性和选择性的固定相，在 HPLC 中受到越来越多的关注。我们的工作组对市售的未取代和对叔丁基取代的 Caltrex(®) 柱进行了深入的研究和表征。它们可用作反相色谱柱，但也支持额外的相互作用。特别是，它们的空间、极性和离子特性与传统的烷基键合相不同。然而，疏水相互作用也存在差异，因为在冠醚键合层上或内部的吸附和分配相互作用与烷基键合层的不同。已经发现固定相疏水性的相对强度取决于流动相中的甲醇浓度。通常，它们的相互作用强度对流动相条件的依赖性，例如氢键能力随甲醇含量降低而变化的强度，在不同的相中也不相似。这可能使冠醚键合固定相更适合于在流动相极端组成下的分析。本文综述了 Caltrex(®) 柱的合成、保留和选择性性质。
