Desmet Gert, Clicq David, Nguyen Dao T-T, Guillarme Davy, Rudaz Serge, Veuthey Jean-Luc, Vervoort Nico, Torok Gabriella, Cabooter Deirdre, Gzil Piotr
Department of Chemical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
Anal Chem. 2006 Apr 1;78(7):2150-62. doi: 10.1021/ac051280+.
It is demonstrated that the kinetic plot representation of experimental plate height data can also account for practical constraints on the column length, the peak width, the viscous heating, and the mobile-phase velocity without needing any iterative solution routine. This implies that the best possible kinetic performance to be expected from a given tested support under any possible set of practical optimization constraints can always be found using a directly responding calculation spreadsheet template. To show how the resulting constrained kinetic plots can be used as a powerful design and selection tool, the method has been applied to a series of plate height measurements performed on a number of different commercial columns for the same component (butyl-parabene) and mobile-phase composition. The method, for example, allows one to account for the fact that the advantageous solutions displayed by the silica monolith and 5 microm particle columns in the large plate number range of the free kinetic plot are no longer accessible if applying a maximal column length constraint of Lmax = 30 cm. In the plate number range that remains accessible, the investigated sub-2 mum particle columns in any case perform (at least for the presently considered parabene separation) better than the 3.5 mum particle columns or silica monolith, especially if considering the use of system pressures exceeding 400 bar. The constrained kinetic plot method can also be used to select the best-suited column length from an available product gamma to perform a separation with a preset number of plates. One of the optimization results that is obtained in this case is that sometimes a significant gain in analysis time can be obtained by selecting a longer column, yielding the desired plate number at a larger velocity than that for a shorter column.
结果表明，实验塔板高度数据的动力学曲线表示法也能考虑到柱长、峰宽、粘性加热和流动相速度等实际限制因素，而无需任何迭代求解程序。这意味着，在任何可能的实际优化约束条件下，使用直接响应的计算电子表格模板总能找到给定测试载体所能达到的最佳动力学性能。为了展示所得的受限动力学曲线如何用作强大的设计和选择工具，该方法已应用于对同一组分（丁基对羟基苯甲酸酯）和流动相组成在多个不同商业柱上进行的一系列塔板高度测量。例如，该方法能考虑到这样一个事实：如果施加最大柱长限制Lmax = 30 cm，那么在自由动力学曲线的大塔板数范围内，硅胶整体柱和5微米粒径颗粒柱所显示的有利解决方案将不再可行。在仍可达到的塔板数范围内，无论如何，所研究的亚2微米粒径颗粒柱（至少对于目前所考虑的对羟基苯甲酸酯分离）的性能都优于3.5微米粒径颗粒柱或硅胶整体柱，特别是在考虑使用超过400 bar的系统压力时。受限动力学曲线方法还可用于从现有产品系列中选择最适合的柱长，以进行具有预设塔板数的分离。在这种情况下获得的一个优化结果是，有时通过选择较长的柱，以比短柱更大的流速获得所需的塔板数，可显著缩短分析时间。
