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One of the biggest problems of producing magnetic beads when scaling up the production is that compared with smaller lot production, larger lot production seems to result in a much larger disproportionate loss of beads. This seems to happen even when the beads are produced in conditions that are similar to the small lot production in a magnetic separation process. The assumption is that when you scale up a process, you will have greater efficiency, but this does not happen when scaling up production of magnetic beads using classical separators.

This post is about biomagnetic separation in the production of magnetic beads for IVD kits. If you want to know its most important elements, download our free ebook The basic guide to use biomagnetic separation in production processes:

## What is going on?

When one uses standard (non-homogeneous) separations devices, the magnetic field decreases with distance from the magnet. The magnetic forces are related to the field variation and so also decrease with distance from the magnet. When one scales up magnetic bead processing, the distance from the magnet increases, but the weight of the magnet cannot be increased proportionally to offset this distance.  Worse yet, both the magnetic force and magnetic field usually scale up differently with an increase in magnet volume.

The consequence of the above is that in larger lot volumes, magnetic beads situated farther from the magnets experience lower forces. Lower forces increase the loss of beads during the processing time and also (because they are attached to the beads), a loss of biomolecules. If you want to overcome this, you need to wait more time to allow the farther beads to travel to the retention zone. But if one does this, the beads that are close to the magnet will experience high magnetic forces for a longer period of time and increase the probability that beads will aggregate. Therefore, one has to balance material loss due to distance from the magnet with material and functional loss due to aggregation.

The only way to overcome losses resulting from the above problems is to change from using a standard biomagnetic separation device to using one of the new devices that generates homogeneous forces regardless of the bead distance from the magnets.

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