At present molecular weight cut-offs (MWCO) are at 12-14000 Daltons which is the standard rating, 1350 Daltons, 3500 Daltons and 7000 Daltons.

We are in the process of developing membranes with cutoffs at different levels and hope to introduce these in 2000, meanwhile a larger range of cutoffs is available from MEDICELL INTERNATIONAL who stock membranes with cutoffs from 50 to 2,000,000 Daltons.

Please note that cutoffs should be regarded as a guide and the permeability of the membrane to any particular molecule will depend on factors other than simple molecular weight, for example shape or volatility of the solution. It is always advisable to use a membrane with a cut off well below the molecular weight of the molecule to be retained. See also our disclaimer.