Department of Analytical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, SK-040 01, Košice, Slovak Republic.
Department of Organic Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, SK-040 01, Košice, Slovak Republic.
J Chromatogr A. 2019 Sep 13;1601:178-188. doi: 10.1016/j.chroma.2019.04.070. Epub 2019 Apr 29.
Three immobilized polysaccharide chiral stationary phases, Chiralpak IA, Chiralpak IB and Chiralpak IC, were used for the study of enantioseparation of 36 derivatives of natural indole phytoalexins, in most cases bioactive, including racemic spirobrassinin, 1-methoxyspirobrassinin and 1-methoxyspirobrassinol methyl ether. Almost all analytes were baseline resolved at least on two different polysaccharide columns in normal phase mode. The effects of mobile phase composition, the analyte structure and the column temperature on the retention and enantioseparation were investigated. Evaluation of the corresponding thermodynamic parameters using van´t Hoff plots (ln k versus 1/T) in the temperature range -15 to 50 °C indicated that separations were enthalpy controlled in most cases, but some entropy controlled separations were also observed. Moreover, unusual phenomenon, an increase retention with increasing temperature accompanied with increased resolution was observed on the Chiralpak IC column. The elution order of enantiomers was determined in some cases and reversed elution order was also observed.
三种固定化多糖手性固定相，Chiralpak IA、Chiralpak IB 和 Chiralpak IC，被用于研究 36 种天然吲哚植物抗毒素衍生物的对映体分离，其中大多数是生物活性的，包括外消旋螺旋 Brassinin、1-甲氧基螺旋 Brassinin 和 1-甲氧基螺旋 Brassinol 甲基醚。在正相模式下，几乎所有分析物都至少在两种不同的多糖柱上达到基线分离。考察了流动相组成、分析物结构和柱温对保留和对映体分离的影响。使用 van't Hoff 图（ln k 与 1/T 的关系）在-15 至 50°C 的温度范围内评估相应的热力学参数表明，大多数情况下分离是焓控制的，但也观察到一些熵控制的分离。此外，在 Chiralpak IC 柱上观察到了一种不寻常的现象，即随着温度的升高，保留时间增加，同时分辨率也增加。在某些情况下确定了对映体的洗脱顺序，也观察到了反转洗脱顺序。
