Analytical Research and Development, Amgen, Inc., One Amgen Center Drive, Thousand Oaks, CA 91320, USA.
Molecules. 2013 Dec 19;19(1):9-21. doi: 10.3390/molecules19010009.
Enantioseparation is largely based on the formation of transitional complexes, the solvation species, the stationary phase configurations or the diastereomeric complexes formed by analytes and the chiral stationary phase. Temperature and the chemical nature and composition of the eluent play significant roles during that process. In this study; unique temperature-induced behaviors were observed during the enantioseparation of Koga tetraamines, also known as Koga bases, on polysaccharide chiral stationary phases, in which van't Hoff plots were acquired over a temperature range of 10 °C to 40 °C with 5 °C increments. Koga bases were eluted by a mixture of methanol and 2-propanol with 0.03% triethylamine as a modifier. The van't Hoff plots are linear in the case of eluent containing equal volumes of methanol and 2-propanol. Increasing 2-propanol concentration from 50% to 85% in volume led to non-linear van't Hoff plots over the entire temperature range studied. Examination of the individual non-linear plots revealed two linear regions of 10 °C-20 °C and 20 °C-40 °C. Transition from one linear region to the other at 20 °C indicates alterations of chiral stationary phase conformation and/or enantioseparation mechanism as a result of temperature changes.
对映体分离主要基于过渡态络合物、溶剂化物种、固定相构型或分析物与手性固定相形成的非对映络合物。在这个过程中，温度以及洗脱液的化学性质和组成起着重要的作用。在本研究中，在多糖手性固定相上对 Koga 四胺（也称为 Koga 碱）进行对映体分离时，观察到独特的温度诱导行为，其中在 10°C 至 40°C 的温度范围内以 5°C 的增量获得范特霍夫图。Koga 碱由甲醇和 2-丙醇的混合物洗脱，其中含有 0.03%三乙胺作为改性剂。在甲醇和 2-丙醇体积相等的洗脱液中，范特霍夫图是线性的。在整个研究温度范围内，2-丙醇浓度从 50%增加到 85%导致范特霍夫图非线性。检查各个非线性图揭示了 10°C-20°C 和 20°C-40°C 的两个线性区域。在 20°C 时从一个线性区域向另一个线性区域的转变表明手性固定相构象和/或对映体分离机制因温度变化而发生变化。
