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Why the force over different volume bottles is constant in advanced Magnetic Bead Separation Systems?

The most common mistake when attempting to scale up production of magnetic beads using a classical magnetic separation rack is to use the same magnetic field that was used at smaller volumes. But keeping the magnetic field constant at different volumes will not give you the same results because the separation conditions are completely different.

Download our Free Guide on Biomagnetic Separation Scale-up HERE.

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:

Magnetic force and magnetic field

The important thing to realize when determining conditions for scaling up magnetic separation processes is that the magnetic force is not related directly to the magnetic field, but is related to the spatial variation of the magnetic field. The magnetic force is the Gradient of the product of the Magnetic Field and the bead magnetic moment. Standard magnetic separation racks generate field profiles where the value changes with the distance from the magnet. Thus, while the magnetic field value is below the saturation field, the magnetic moment of the superparamagnetic beads will be change proportionally to it.

Bead conditions in a magnetic separation rack

In this case the force is proportional to the gradient of the square of the magnetic field, the force that the beads experience in classical magnetic separation racks will change with the distance from the magnet. This is a major problem when scaling up production because beads experience very different conditions relative to what they experience during the production in smaller volumes.

Why advanced separation systems offer valuable solutions

Advanced biomagnetic separation systems such as SEPMAG, however, generate homogeneous forces that do not vary with bead distance from the magnets. The force is maintained at a constant level by keeping the field high enough to magnetically saturate the beads. This allows the field to change linearly with distance.

In this case, the distance of the beads from the magnet would have no effect on the results of the production and, therefore, the volume of the lot would not affect the separation behavior of the production process. The magnetic force over the beads will be the same in all the cases, then also the separation speed.

Therefore, using more advanced homogeneous Magnetic Bead Separation systems allows your company to scale up production without the need for lengthy and costly validation experiments since the separation conditions do not change with volume size.

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:

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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