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Why do Larger Non-Homogeneous Magnetic Separators Have Higher Losses of Magnetic Beads and Biomolecules?

By 26 de September de 2013June 18th, 2024No Comments

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.

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This post is about Magnetic Bead 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 Magnetic Bead 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.

magnetic separation rack force at farthest beads

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 Magnetic Bead Separation processes:

Check to access to FREE eBooks on the subject, or contact us. We will be glad to help you to achieve an efficient magnetic bead separation process!


magnetic separation rack

Lluis M. Martínez | SEPMAG Chief Scientific Officer

Founder of SEPMAG, Lluis holds a PhD in Magnetic Materials by the UAB. He has conducted research at German and Spanish academic institutions. Having worked in companies in Ireland, USA and Spain, he has more than 20 years of experience applying magnetic materials and sensors to industrial products and processes. He has filed several international patents on the field and co-authored more than 20 scientific papers, most of them on the subject of magnetic particle movement.

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