Gzil P, De Smet J, Vervoort N, Verelst H, Baron G V, Desmet G
Department of Chemical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
J Chromatogr A. 2004 Mar 19;1030(1-2):53-62. doi: 10.1016/j.chroma.2003.12.038.
The chromatographic performance of several straightforward two-dimensional etched packed bed column lay-outs (equilaterally staggered arrays of, respectively, circular, hexagonal, and diamond-like pillars) has been compared using commercial computational fluid dynamics software. In all cases, the bed porosity was kept at epsilon = 0.4 and a retained component with zone capacity ratio k" = 2 was considered. Exploring the use of six different possible characteristic dimensions to bring the Van Deemter plots of the three different considered particle shapes into agreement, none of them yielded a perfect agreement. Using the pillar volume-based equivalent cylinder diameter (deq) as the characteristic dimension, the diamond-like pillars yielded a significantly smaller h(min) value than the cylinders and the hexagons (h(min) approximately equal to 0.74 for the former versus h(min) approximately equal to 0.83 for the two latter). Including the flow resistance into the analysis, it was found that the "hydrodynamic" shape of the particles has an important influence on the separation impedance E. The more axially elongated diamond pillars yielded an Emin number as small Emin = 180 (for a retained component with k" = 2), i.e. about 40% smaller than the cylinders and the hexagons (Emin = 300-330). The obtained h(min) and Emin values are also significantly smaller than the values often cited for the best possible packed bed HPLC columns. We believe this is a consequence of the assumed perfect homogeneity of the etched structures, and hence hints at the potential benefits of perfectly ordered chromatographic columns, as was already inferred by Knox [J. Chromatogr. A 831 (1999) 3; 960 (2002) 7] and He et al. [Anal. Chem. 70 (1998) 3790].
使用商业计算流体动力学软件比较了几种简单的二维蚀刻填充床柱布局（分别为圆形、六边形和类菱形柱的等边交错阵列）的色谱性能。在所有情况下，床层孔隙率保持在ε = 0.4，并考虑了保留组分的区容量比k" = 2。探索使用六种不同的可能特征尺寸以使三种不同考虑的颗粒形状的范德姆特图一致，但没有一种能产生完美的一致性。使用基于柱体积的等效圆柱直径（deq）作为特征尺寸，类菱形柱产生的h(min)值明显小于圆柱和六边形柱（前者h(min)约等于0.74，而后两者h(min)约等于0.83）。将流动阻力纳入分析后发现，颗粒的“流体动力学”形状对分离阻抗E有重要影响。轴向拉长程度更高的菱形柱产生的Emin数小至Emin = 180（对于保留组分k" = 2），即比圆柱和六边形柱小约40%（Emin = 300 - 330）。获得的h(min)和Emin值也明显小于通常引用的最佳填充床HPLC柱的值。我们认为这是蚀刻结构假定的完美均匀性的结果，因此暗示了完美有序色谱柱的潜在益处，正如Knox [《色谱杂志A》831 (1999) 3；960 (2002) 7] 和He等人 [《分析化学》70 (1998) 3790] 已经推断的那样。
