I appreciate the sentiment, capernicus1.
The essence of it is outlined in my first post.
As mentioned, you’re basically looking at point charges in a magnetic field. Now, in such a system, given no other influence, there is no doubt about the way in which the charges (ions) will be affected. The relevant ones in this scenario, the ones moving perpendicular to the lines of the magnetic field, will experience an acceleration that’s perpendicular to both their current velocity and the field lines. Because the lines are constant and the velocity changes according to the acceleration, this will cause them to move in circles inside the field.
So far, I’ve made no assumptions. That’s simply how it works.
The problem however, with biological systems is the huge list of external actions on the system. For one thing, your charges are in a solution (blood) so there will be a concentration gradient which will affect their movement. They’re probably not moving at the same speed either, so not all of them will be “caught” in the field - if the speed is too great, they will leave the field before finishing a complete circular movement. Different types of ions have different masses so they’ll experience different accelerations - you get the same problem as with speed. And so on.. (different electric fields, the fact that ions will be colliding, changes in the speed of the blood flowing by etc.)
So there are a lot of things that can interfere with the movement of the charges.
However, my point is that theoretically there’s no reason why it shouldn’t be possible to construct a magnet in such a way that it could indeed cause an accumulation of ions when placed near a bunch of moving ions.