Department of Chemistry, Smith and Kolthoff Halls, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, MN 55455, USA.
J Chromatogr A. 2011 Jan 7;1218(1):64-73. doi: 10.1016/j.chroma.2010.10.096. Epub 2010 Oct 31.
In this work we develop a practical approach to optimization in comprehensive two dimensional liquid chromatography (LC x LC) which incorporates the important under-sampling correction and is based on the previously developed gradient implementation of the Poppe approach to optimizing peak capacity. The Poppe method allows the determination of the column length, flow rate as well as initial and final eluent compositions that maximize the peak capacity at a given gradient time. It was assumed that gradient elution is applied in both dimensions and that various practical constraints are imposed on both the initial and final mobile phase composition in the first dimension separation. It was convenient to consider four different classes of solute sets differing in their retention properties. The major finding of this study is that the under-sampling effect is very important and causes some unexpected results including the important counter-intuitive observation that under certain conditions the optimum effective LC x LC peak capacity is obtained when the first dimension is deliberately run under sub-optimal conditions. In addition, we found that the optimum sampling rate in this study is rather slower than reported in previous studies and that it increases with longer first dimension gradient times.
在这项工作中，我们开发了一种实用的综合二维液相色谱（LCxLC）优化方法，该方法结合了重要的欠采样校正，并且基于先前开发的 Poppe 方法来优化峰容量的梯度实现。Poppe 方法允许确定柱长、流速以及初始和最终洗脱液组成，从而在给定梯度时间内最大化峰容量。假设梯度洗脱应用于两个维度，并且在第一维分离中对初始和最终流动相组成施加各种实际限制。方便起见，考虑了在保留性质上不同的四种不同的溶质集。本研究的主要发现是，欠采样效应非常重要，会导致一些意外的结果，包括一个重要的反直觉观察结果，即在某些条件下，当第一维故意在次优条件下运行时，可获得最佳的有效 LCxLC 峰容量。此外，我们发现，本研究中的最佳采样率比以前的研究报告的要慢，并且随着第一维梯度时间的延长而增加。
