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Posted on Thu, Aug 15, 2013

Why Do Different Batch Volumes Require Different Magnetic Fields?

Do you want to learn how to take the most of your magnetic separation rack? There are lots of common mistakes related to the scale-up of biomagnetic separation processes, and lots of them imply the use of non-homogeneous magnetic racks.

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

Knowing these mistakes is a good idea in order to be successful in your scale-up and avoid making mistakes others have already made. 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:

Mistakes when scaling up non-homogeneous biomagnetic separation processes

One of the most common mistakes people make when attempting to scale up non-homogeneous biomagnetic separation processes is that they tend to use the exact same magnetic field with different volumes. Simply put, this will not work.

Sometimes people relate the force generated by a powerful magnet directly with the high magnetic field that magnet produces. However, the intensity of the magnetic field is not the relevant parameter for determining the magnetic force. For example, if you have a homogeneous magnetic field that has high intensity such as the field generated by an MRI magnet, the assumption is that the intensity of this magnetic field determines the amount of magnetic force.

If the field is homogenous in biomagnetic separation, no matter how high the field is, the force is equal to zero and particles will not move but will instead align with the field.

A magnet has a force because it generates a field that changes with distance. It is this change that produces the magnetic force. Depending on the magnetic characteristics of the beads the magnetic force is related to either the gradient of the magnetic field or (if the field is very low) with the gradient of the magnetic field squared. Under any circumstance, however, the force will vary depending on the characteristics of the beads and the spatial variation of the magnetic field.

Homogeneous vs non-homogeneous magnetic separation rack


When a company needs to scale up a biomagnetic separation process, it is imperative that they do not pay attention to the magnetic field per se, but instead pay attention to how the magnetic field varies. For homogeneous biomagnetic separation systems, the force is constant and well-defined so scaling up is typically straightforward. For non-homogeneous systems, you need to take a close look at the exact conditions your system has (e.g. variation of the magnetic field, characteristics of the beads and characteristics of the magnetic field) before scaling up your process. When you do decide to scale up your process, you must scale up the magnetic force and not the magnetic field.

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!

Dr. Lluís Martínez 

magnetic separation rack

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