A membrane rating expressed as molecular weight is not a direct conversion of a pore dimension in micrometres.
Define the Interface or Transport Basis
Repligen's dialysis FAQ describes MWCO through a specified solute-retention test and distinguishes it from a metric size. Molecular mass and geometric dimensions do not provide a universal direct conversion; shape and the actual retention method matter. The FAQ's stated MWCO definition belongs to its dialysis context.
Review a Hypothetical Comparison
Imagine two supplier reports: one labels a membrane 0.1 micrometres and another labels one 20 kDa. Those labels alone cannot rank which retains a particular dissolved molecule. In a separate hypothetical method test, 47 mg of an initial 50 mg remains on the specified side after the defined interval, giving 94% retention. That is an observed test fraction, not proof that a membrane labeled 20 kDa retains every 20 kDa substance in every filtration arrangement.
Keep the Evidence with the Decision
Request the rating's test solute, retention criterion, duration and contacting conditions. Identify whether the intended task is dialysis, pressure filtration or another process. Compare the actual molecule and medium against the test basis. Keep dimensions, molecular mass and measured retention in separate fields rather than converting one label into another with a guessed factor.
The decision is whether the rating supports the required retention question. It does not identify a sterilizing capability, universal cutoff boundary or membrane choice for an HM machine.
Does the reported membrane rating define the retention behavior required for this solute?
This blank worksheet is for your own project. It contains no H M machine trial result.
| Review field | Reference or result | Responsible person |
|---|---|---|
| Pore dimension or MWCO label and units | To complete | To complete |
| Supplier retention-test definition | To complete | To complete |
| Actual solute and contacting process | To complete | To complete |
| Measured retention under comparable conditions | To complete | To complete |
Customer Questions
Can micrometres be universally converted into kDa?
No. Geometric size and molecular mass do not have one universal conversion.
Is MWCO an absolute boundary for every molecule?
Check the supplier's retention definition and the actual molecule; the label alone is incomplete.
Can dialysis ratings be transferred directly to pressure filtration?
The contacting method and test conditions need their own comparison.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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