Cross flow filtration of RNA extracts by hollow fiber membrane

The feasibility of using ultrafiltration to concentrate RNA was investigated. Ultrafiltration flux and solute retentivity were affected by membrane cut-off and inlet pressure. The RNA can be concentrated by selecting a hydraulically permeable membrane (PM 30) and then operating the system at a sufficiently high pressure (2.07 · 10⁵ Nm⁻²) and a high recirculation rate (150 cm⁻¹). The use of this procedure was limited to a high-flux regime. However, a very high retentivity of macrosolute was achieved. The effect of transmembrane pressure on the apparent mass transfer coefficient in the “gel polarization model” was discussed and related to ultrafiltration flux.