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During non-homogeneous separation in a magnetic separation rack, in order to generate a magnetic force, you need to use magnet arrangements to create a variation in the magnetic field. In this situation, the magnetic force will always vary with distance from the magnets.

This post is about biomagnetic separation with a magnetic separation rack, and how to scale-up this process. If you are interested in this topic, download our free ebook The Basic Guide to Scale-up Biomagnetic Separation Processes:

For example, if you use a small magnetic separation rack with a bottle diameter of 5 cm and small magnets, the farthest beads from the magnets experience forces of more than 4 T/m. If you increase the bottle diameter, the farthest beads will experience a smaller force. So in this situation you have the same magnetic field profile, but a longer distance which results in a smaller force at the outer boundaries of where the beads lie.

If you then decide to increase magnetic separation rack size, the force typically does not increase as quickly as volume size. Therefore, you will have less magnetic force, a slower speed of bead movement over a larger distance (i.e. larger volumes = longer distance the beads must travel to the retention zone). This situation requires either much longer separation times in order to get comparable losses to smaller production sizes or accepting larger losses at the same separation times.

## Advantages of homogeneous separation systems

On the other hand, homogeneous separation systems use a constant force throughout the entire volume of the vessel. Because of this it is much easier to determine how to scale up the process when one wants to use a larger vessel. In these systems, the separation time is then dependent only on the size of the bottle (i.e. the distance the beads must travel).

Don't forget to check these posts from our blog in order to get a deeper insight into the scaling-up of biomagnetic separation processes: