Department of Chemistry, Gustavus Adolphus College, Saint Peter, MN 56082, USA.
J Chromatogr A. 2010 Sep 3;1217(36):5700-9. doi: 10.1016/j.chroma.2010.07.009. Epub 2010 Jul 15.
Comprehensive two-dimensional liquid chromatography (2DLC) offers a number of practical advantages over optimized one-dimensional LC in peak capacity and thus in resolving power. The traditional "product rule" for overall peak capacity for a 2DLC system significantly overestimates peak capacity because it neglects under-sampling of the first dimension separation. Here we expand on previous work by more closely examining the effects of the first dimension peak capacity and gradient time, and the second dimension cycle times on the overall peak capacity of the 2DLC system. We also examine the effects of re-equilibration time on under-sampling as measured by the under-sampling factor and the influence of molecular type (peptide vs. small molecule) on peak capacity. We show that in fast 2D separations (less than 1h), the second dimension is more important than the first dimension in determining overall peak capacity and conclude that extreme measures to enhance the first dimension peak capacity are usually unwarranted. We also examine the influence of sample types (small molecules vs. peptides) on second dimension peak capacity and peak capacity production rates, and how the sample type influences optimum second dimension gradient and re-equilibration times.
二维液相色谱（2DLC）在峰容量方面相对于优化的一维 LC 具有许多实际优势，因此在分辨率方面也具有优势。二维 LC 系统的整体峰容量的传统“乘积规则”严重高估了峰容量，因为它忽略了一维分离的欠采样。在这里，我们通过更仔细地检查第一维峰容量和梯度时间的影响，以及第二维循环时间对二维 LC 系统整体峰容量的影响，扩展了以前的工作。我们还检查了再平衡时间对欠采样的影响，如欠采样因子所测量的，以及分子类型（肽与小分子）对峰容量的影响。我们表明，在快速的二维分离（小于 1 小时）中，第二维在确定整体峰容量方面比第一维更为重要，并得出结论，通常不需要采取极端措施来增强第一维峰容量。我们还检查了样品类型（小分子与肽）对第二维峰容量和峰容量生产速率的影响，以及样品类型如何影响最佳第二维梯度和再平衡时间。
