Table 1:
Sartobind® STIC Pico and Sartobind® STIC Nano are the smallest scalable representatives of the Sartobind® STIC membrane adsorber family. STIC is a salt-tolerant anion-exchange membrane effective at removing contaminants in buffers containing up to 200 mM NaCl, saving time and reducing costs by avoiding buffer changes. The small size and high throughput of these capsules make them perfect for use on automated chromatography systems such as the popular ÄKTA® series offered by GE Biosciences.
Although both Pico and Nano capsules are designed for high flow rates, the array of valves, pumps, monitors and the flow restrictor found in a typical flow path for gel chromatography can cause unacceptable pressures at their designed flow rates. Although a lower flow rate will reduce pressure in the system, this does not take advantage of the rapid processing offered by Sartobind® membrane adsorbers. A method designed to maintain ideal conditions without generating excessive pressure is described below, along with typical results for Sartobind® STIC used in flow-through polishing mode.
Table 1:
Experience with different versions of liquid chromatography systems has resulted in a number of recommendations to ensure success with Sartobind® small-scale polishing devices. Before they are used, air must be purged from both Pico and Nano capsules with a syringe as described in the instruction manual. After connecting Sartobind® capsules, it is strongly recommended that the sanitizing and flushing procedure outlined in the instruction manual be followed to ensure that air is removed and residual glycerol is washed out. In addition, it is very important to use a simple flow path on the chromatography system when using Sartobind® Pico or Nano. With the flow path adjusted for bypassing as many valves as possible, the mixer, and the flow restrictor, pressure can be maintained within limits specified for Sartobind® capsules. Finally, despite filtering protein or virus samples before applying a solution to the membrane, proteins may still form aggregates. For that reason, placing a 0.2-µm filter in line before the capsule can remove aggregates and prevent clogging of the Sartobind® membrane.
ResultsSartobind® STIC membranes used in polishing applications are extremely efficient at removing contaminating DNA, endotoxin, viruses, and host-cell proteins in the presence of NaCl. Table 1 provides typical log reduction values for these common contaminants.
ConclusionsPolishing applications such as removal of host-cell proteins, DNA, endotoxin, and viruses can be achieved with small-scale Sartobind® STIC membranes containing up to 200 mM NaCl. These devices can be used successfully in polishing mode on liquid chromatography systems at acceptable pressures if easily implemented changes to the flow path are made.
Author Details
Gregory Krueger is a field marketing manager in purification technologies for Sartorius Stedim Biotech,