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Two conditions to have constant magnetic force regardless the lot volume

It is vitally important to understand the process and all of the variables of the process when scaling up a Magnetic Bead Separation in a magnetic separation rack. If you do not understand the details of your process, you will throw away your initial investment you made in validating your initial process and jeopardize the product’s time to market.

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:

Understanding how to maintain constant magnetic force

In biomagnetic separation processes, magnetic beads move because the magnetic force is greater than the drag force on the beads due to the buffer viscosity. Therefore, the key parameter to understand is the magnetic force. The magnetic force depends both on how the magnetic field changes spatially (i.e. the magnetic field gradient) and on the strength of the magnetization of the magnetic beads.

The two conditions that must be met in order for a constant magnetic force to be maintained in Magnetic Bead Separation processes are:

  1. The magnetic field needs to vary linearly with the distance of the beads from the magnet.
  2. The beads should be magnetically saturated so that the field is high enough (e.g. B < 0.1 T for magnetite).

Advanced separation systems fulfill both conditions

The newer, more advanced homogeneous Magnetic Bead Separation systems such as SEPMAG fulfill these two conditions in virtually any volume desired. This is accomplished because the homogeneous systems are designed with a cylindrical geometry comprised of a constant radial magnetic field in the core. In these systems, the gradient is adjusted so that the magnetic field is over 0.1 T everywhere except in a small area around the axis.

Because of this constant force in the advanced systems, SEPMAG guarantees that no less than 93% of the beads are saturated when the process starts. After a few seconds, all of the beads have moved out of the central region and are in optimal conditions. The initial 7% of beads not in optimal conditions are considered the practical limit of the device.

Advanced homogeneous separation systems such as SEPMAG are therefore, easy to scale up because these conditions are determined in smaller volumes and remain the same when scaled up to larger volumes. When using a standard magnetic separation rack, volume matters because the beads feel different forces relative to their distance from the magnets. Scaling up a process with standard devices forces the company to conduct validation and quality control experiments in order to find the new correct parameters in the larger volumes.

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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