Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
J Chromatogr A. 2021 Jun 21;1647:462167. doi: 10.1016/j.chroma.2021.462167. Epub 2021 Apr 22.
Simultaneously reducing the bed-height and increasing the area of cross-section, while keeping the bed-volume the same, would substantially reduce the pressure drop across a process chromatography column. This would minimize problems such as resin compaction and non-uniformity in column packing, which are commonly faced when using soft chromatographic media. However, the increase in macroscale convective dispersion due to the increase in column diameter, and the resultant loss in resolution would far outweigh any potential benefit. Cuboid-packed bed devices have lower macroscale convective dispersion compared to their equivalent cylindrical columns. In this paper, we discuss how and why a flat cuboid chromatography device having a short bed-height gives better protein separation, at a significantly lower pressure drop, than a taller column having the same bed-volume. First, we explored this option based on computational fluid dynamic (CFD) simulations. Depending on the flow rate, the pressure drop across the flat cuboid device was lower than that in the tall column by a factor of 6.35 to 6.4 (i.e. less than 1/6 the pressure). The CFD results also confirmed that the macroscale convective dispersion within the flat cuboid device was significantly lower. Head-to-head separation experiments using a 1 mL flat cuboid device having a bed-height of 10 mm, and a 1 mL tall column having a bed-height of 25.8 mm, both packed with the same chromatographic media, were carried out. The number of theoretical plates per unit bed-height was on an average, around 2.5 time times greater with the flat cuboid device, while the total number of theoretical plates in the two devices were comparable. At any given superficial velocity, the height equivalent of a theoretical plate in the tall column was on an average, higher by a factor 2.5. Binary protein separation experiments showed that at any given flow rate, the resolution obtained using the flat cuboid device was significantly higher than that obtained with the tall column. This work opens up the possibility of designing and developing short bed-height chromatography devices for carrying out high-resolution biopharmaceutical purifications, at very low pressures.
同时降低床层高度并增加床层横截面积，而保持床层体积不变，将大大降低过程层析柱的压降。这将最大限度地减少使用软质层析介质时通常会遇到的树脂压实和柱填充不均匀等问题。然而，由于柱直径的增加导致宏观对流弥散的增加，以及分辨率的损失，这将远远超过任何潜在的好处。与等效的圆柱形柱相比，长方体填充床装置的宏观对流弥散较低。在本文中，我们讨论了为什么以及如何使用具有短床层高度的扁平长方体层析设备可以在显著降低压降的情况下，比具有相同床层体积的更高的柱获得更好的蛋白质分离效果。首先，我们基于计算流体动力学（CFD）模拟探索了这种选择。根据流速的不同，扁平长方体装置的压降比高柱的压降低 6.35 至 6.4 倍（即压力小于 1/6）。CFD 结果还证实，扁平长方体装置内的宏观对流弥散显著降低。使用具有 10mm 床层高度的 1mL 扁平长方体装置和具有 25.8mm 床层高度的 1mL 高柱进行了头对头分离实验，两者均填充相同的层析介质。单位床层高度的理论塔板数平均约为扁平长方体装置的 2.5 倍，而两个装置的总理论塔板数相当。在任何给定的表面速度下，高柱的理论塔板高度当量平均高出 2.5 倍。二元蛋白质分离实验表明，在任何给定的流速下，使用扁平长方体装置获得的分辨率都明显高于使用高柱获得的分辨率。这项工作为设计和开发短床层高度的层析设备用于进行高通量生物制药的高分辨率纯化提供了可能性，且压力非常低。
