Table of Contents
What is the purpose of diafiltration?
The aim of diafiltration is to replace the solvent or buffer used to suspend cells or macromolecules. The main applications are desalting of proteins and buffer exchange, for example, between chromatography steps. As shown in Figure 11.37, new solvent or buffer is added to the feed material during membrane filtration.
What is the difference between ultrafiltration and diafiltration?
What’s the difference between ultrafiltration and diafiltration? UF uses a semipermeable membrane to separate molecules based on size and is typically used for purification and concentration. DF is the process of adding back a different buffer or solvent after UF.
How is Diavolume calculated?
A diavolume is defined as the “total buffer volume introduced to the operation during diafiltration [divided] by the [initial] retentate volume” [7]. The hemoglobin yield was calculated as (total final Hb mass)/(initial retentate Hb mass); it was used as a measure of Hb retained by the filter.
Is diafiltration the same as TFF?
Finally, Diafiltration (DF) is a TFF process that can be performed in combination with any of the other categories of separation to enhance either product yield or purity. During DF, buffer is introduced into the recycle tank while filtrate is removed from the unit operation.
What is a diafiltration volume?
Diafiltration Volume One diafiltration volume equals the initial volume in which the molecule of interest is suspended. The number of diafiltration volumes required depends on whether the permeating species is freely passing (salts, buffers, solvents) or partially retained.
What is crossflow rate?
The crossflow velocity is the rate of the solution flow through the feed channel and across the membrane. It provides the force that sweeps away molecules that can foul the membrane and restrict filtrate flow.
What is concentration and diafiltration?
Diafiltration is a technique that uses ultrafiltration membranes to completely remove, replace, or lower the concentration of salts or solvents from solutions containing proteins, peptides, nucleic acids, and other biomolecules.
What does retentate mean?
That which is retained
retentate (plural retentates) That which is retained, for example by a filter or porous membrane.
What is filtrate and retentate?
RETENTATE: It is the acid insoluble fraction of the cellular pool which is retained in the cheesecloth. FILTRATE: It is the acid soluble fraction that passes through the cheesecloth.
What does a UF membrane remove?
Ultrafiltration membrane filtration (UF) is a low pressure membrane process for water treatment that is designed to remove turbidity causing particles including those comprised of suspended solids, bacteria, colloidal matter and proteins.
Why is concentration carried out prior to diafiltration?
Commonly, sample concentration is performed first to reduce the overall sample volume, followed by diafiltration. This approach significantly reduces the amount of diafiltration buffer required.
How does a crossflow work?
Cross flow filtration is when the flow is applied tangentially across the membrane surface. As feed flows across the membrane surface, filtrate passes through while concentrate accumulates at the opposite end of the membrane.
What is a TFF?
Tangential flow filtration (TFF), also known as Cross-flow filtration, is a process of separation widely used in bio-pharmaceutical and food industries.