Carr Peter W, Wang Xiaoli, Stoll Dwight R
Department of Chemistry, University of Minnesota, 207 Pleasant Street, S.E., Minneapolis, Minnesota 55455, USA.
Anal Chem. 2009 Jul 1;81(13):5342-53. doi: 10.1021/ac9001244.
Although the principles of optimization of high-performance liquid chromatography (HPLC) have a long history starting with the work of Giddings in the 1960s and continuing with work by Knox and Guiochon extending into the 1990s we continue to see statements that flatly contradict theory. A prominent example is the notion that optimum "performance", as measured by plate count, is always obtained by operating conventional length columns (e.g., 5-15 cm) at eluent velocities corresponding to the minimum plate height in the van Deemter curve. In the past decade the introduction of "Poppe plots" by Poppe and "kinetic plots" by Desmet and others has simplified the selection of "optimum" conditions, but it is evident that many workers are not entirely comfortable with this framework. Here we derive a set of simple, yet accurate, equations that allow rapid calculation of the column length and eluent velocity that will give either the maximum plate count in a given time or a given plate count in the shortest time. Equations are developed for the optimum column length, eluent velocity, and thus plate count for both the cases when particle size is preselected and when particle size is optimized along with eluent velocity and column length. Although both of these situations have been previously considered the implications of the resulting equations have not been previously made explicit. Lack of full understanding of the consequences of the differences between these two cases is very important and responsible for many erroneous conclusions. The simple closed-form equations that result from this work complement the graphical, iterative approaches of Poppe and Desmet; the resulting compact framework allows practitioners to rapidly and effectively find the operating parameters needed to achieve a specific separation goal in the shortest time and to compare emerging technologies (e.g., high pressure, high temperature, and different particle types) in terms of their impact on achievable plate counts and speeds in HPLC. A Web-based calculator based on the equations presented here is now available (http://homepages.gac.edu/ approximately dstoll/calculators/optimize.html).
尽管高效液相色谱（HPLC）优化原理的历史悠久，始于20世纪60年代吉丁斯的工作，并随着诺克斯和吉奥雄的工作延续到20世纪90年代，但我们仍不断看到与理论完全相悖的说法。一个突出的例子是这样一种观念，即通过塔板数衡量的最佳“性能”总是在对应于范德姆特曲线中最小塔板高度的洗脱液流速下操作常规长度的色谱柱（例如5 - 15厘米）时获得。在过去十年中，波普引入的“波普图”以及德梅特等人引入的“动力学图”简化了“最佳”条件的选择，但很明显许多研究人员对这个框架并不完全满意。在此，我们推导了一组简单而准确的方程，可快速计算出能在给定时间内给出最大塔板数或在最短时间内给出给定塔板数的色谱柱长度和洗脱液流速。针对预先选择粒径以及粒径与洗脱液流速和色谱柱长度同时优化这两种情况，分别推导了关于最佳色谱柱长度、洗脱液流速以及塔板数的方程。尽管此前这两种情况都已被考虑过，但所得方程的含义此前并未明确阐述。对这两种情况之间差异的后果缺乏全面理解非常重要，并且导致了许多错误结论。这项工作得出的简单封闭式方程补充了波普和德梅特的图形迭代方法；由此产生的紧凑框架使从业者能够在最短时间内快速有效地找到实现特定分离目标所需的操作参数，并根据它们对HPLC中可实现的塔板数和速度的影响来比较新兴技术（例如高压、高温和不同类型的颗粒）。现在有一个基于此处给出的方程的网络计算器（http://homepages.gac.edu/ approximately dstoll/calculators/optimize.html）。
