School of Pharmaceutical Sciences, University of Geneva, CMU - Rue Michel-Servet 1, 1211, Geneva 4, Switzerland; Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU - Rue Michel-Servet 1, 1211, Geneva 4, Switzerland.
School of Pharmaceutical Sciences, University of Geneva, CMU - Rue Michel-Servet 1, 1211, Geneva 4, Switzerland; Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU - Rue Michel-Servet 1, 1211, Geneva 4, Switzerland.
Anal Chim Acta. 2020 Oct 16;1134:84-95. doi: 10.1016/j.aca.2020.07.076. Epub 2020 Aug 18.
The use of unorthodox temperatures, ranging from -5 °C up to 80 °C, have been thoroughly investigated in supercritical fluid chromatography. To this purpose, an initial evaluation of the kinetic and thermodynamic performance has been made with a set of 4 analytes eluting at different percentages of organic co-solvent in the mobile phase (3%-10% - 45%-80%). The van Deemter plots have demonstrated how, at low organic modifier presence, the use of low temperatures did not necessarily translate into worse performance, while high temperatures could pose more issues due to the poor handling of the super/subcritical mobile phase by the chromatographic system. With important percentages of co-solvent, however, high temperatures were fundamental in ensuring better profiles of the van Deemter plots, compared to low temperatures. Pressure plots have demonstrated that gradients reaching elevated percentages of organic modifiers can also be used on stationary phases packed with sub 2 μm silica particles if high temperatures are employed. The thermodynamic evaluation, made via the analysis of van't Hoff plots, indicates the presence of three retention behaviors happening in UHPSFC when switching from high to low temperatures, depending on the co-solvent percentage needed to elute one analyte. Finally, an assessment of the stationary phase stability at high temperatures was performed: the retention times variabilities recorded were minimal (RSD < 2.5%), as well as the peak widths and inlet column pressures were somewhat constant throughout the analyses. In the second part of this study, a focus on potential applications benefiting from such unconventional temperatures has been made. A series of challenging analytes have experienced better chromatographic resolution at either high or low temperatures, providing therefore a potentially interesting tool to analysts during the chromatographic method development process. In conclusion, the UV sensitivity at different temperatures was also taken into consideration, with no significant impact on the quality of the UV signal under any condition.
超临界流体色谱中彻底研究了非传统温度的使用，范围从-5°C 到 80°C。为此，用一组在流动相中有不同有机共溶剂百分比（3%-10%-45%-80%）洗脱的 4 种分析物对动力学和热力学性能进行了初步评估。范德梅尔图表明，在低有机改性剂存在的情况下，低温不一定会导致性能下降，而高温可能会由于色谱系统对超/亚临界流动相的处理不当而产生更多问题。然而，在存在重要共溶剂百分比的情况下，高温对于确保范德梅尔图更好的轮廓至关重要，与低温相比。压力图表明，如果使用高温，也可以在填充有亚 2 µm 硅胶颗粒的固定相上使用达到高有机改性剂百分比的梯度。通过 van't Hoff 图的分析进行的热力学评估表明，当从高温切换到低温时，在 UHPSFC 中存在三种保留行为，这取决于洗脱一种分析物所需的共溶剂百分比。最后，对高温下固定相的稳定性进行了评估：记录的保留时间变化很小（RSD <2.5%），并且峰宽和入口柱压在整个分析过程中基本保持不变。在本研究的第二部分，重点关注了从这种非常规温度中受益的潜在应用。一系列具有挑战性的分析物在高温或低温下经历了更好的色谱分辨率，因此为分析人员在色谱方法开发过程中提供了一个潜在的有趣工具。总之，还考虑了不同温度下的 UV 灵敏度，在任何条件下都不会对 UV 信号的质量产生重大影响。
