Any small volume classic magnetic separation rack is relatively cheap and does a fairly good job at separating magnetic beads. However, if the process involves multiple instances of capture and elution steps, irreversible aggregation becomes a real problem. In small volume separations (i.e. on the order of milliliters), using the appropriate techniques can give you excellent re-suspension results.
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:
Large volume classic magnetic separation racks, however, typically have serious problems with irreversible aggregation. The way to avoid losses in magnetic bead yield is to increase the magnetic force. Since magnetic force in classic separation devices varies with distance, increasing the force causes beads close to the magnet and in the retention zone to experience extremely high forces over a longer period of time.
Consequently, the magnetic beads have a higher probability of being irreversibly aggregated, forming clumps by overcoming the electrostatic barriers that normally keep the beads apart from one another. When the electrostatic barriers are breached, the beads become cross-linked.
This irreversible aggregation and clumping effect in lot consistency is adverse because aliquots for individual kits from the same large volume lot are highly variable. Some beads were exposed only to a low magnetic force and some were exposed to very high forces.
Solutions to common lot inconsistencies
There are two possible ways to deal with these inconsistencies:
- You can devote a large amount of resources (money, materials, time, and personnel) toward recovering beads from the aggregates (i.e. using sonication and long sonication/homogenization cycles).
- You can use a homogeneous biomagnetic separation system like SEPMAG.
Choosing to change production to an advanced homogeneous magnetic separation system like SEPMAG is easier and cheaper in the long run than choosing to recover already aggregated beads. Beads produced with a homogeneous system and a wisely chosen magnetic force value will produce lots that are consistent throughout the entire volume since the same force is felt by all of the beads. In addition, irreversible aggregation is very rare in these systems. Therefore, SEPMAG systems will both increase in-lot consistency and will treat all beads gently and equally during the separation process.
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:
- Why the force over different volume bottles is constant in advanced biomagnetic separation systems?
- Two conditions to have constant magnetic force regardless the lot volume
- How to deal with the 4 typical magnetic separation beads scale up problems?