Magnetic Separation Rack: What Makes a Good One?

What’s magnetic separation?

Magnetic separation is a process of using a magnetic force (magnetic roller in Fig.1) to extract magnetic components (magnetic particles) from a mixture (powdered ore). The result is magnetic material, strongly affected by magnetic fields (called as superparamagnetic) is separated from non-magnetic or less-magnetic material.

In magnetic separation, superparamagnetics require relatively weak magnetic fields to be attracted. Devices to separate these materials usually use magnets that are permanently magnetized. They do not require electricity to maintain their magnetic fields.

How does magnetic separation work?

As shown in the process in Figure.1, when the powdered ore moves on the conveyor belt, magnetic separation uses a magnetic roller to attract magnetic particles, which move farther and fall into the collector on the right side until the magnetic force diminishes while non-magnetic particles fall off the belt into the collector on the left side.

Magnetic separation in mineral processing plants

Figure 1. Magnetic separation in mineral processing plants.

Magnetic separation in biological sample preparations

Magnetic separation is also broadly employed in biology labs for sample preparation, e.g. cfDNA extraction, DNA cleanup, DNA sizing, Chromatin immunoprecipitation(ChIP) , and cell separation as well. It uses magnetic nanoparticles (also called as nanobeads, or beads) to bind the targeted sample. Magnetic beads enabled methods don’t need column or centrifugation. They use magnetic force to aggregate, wash and elute magnetic beads-bound targets. This makes the workflow simple and easy for automation, which leads to higher throughput.

A typical magnetic beads enabled protocol is like the one below used for DNA sizing.

MagVigen DNA size selection workflow

Figure 2. DNA sizing workflow.

  1. Mix: Mix nanoparticles with DNA sample.
  2. Bind: Nanoparticles bind to the desired DNA size fragments.
  3. Wash: Use a magnetic force to aggregate the bound material. Remove unbound materials by aspiration, what remains is the nanoparticle-bound targets.
  4. Elute: Release the bound target size fragments from the nanoparticle. The selected DNA sample is ready for downstream applications.

What’s a magnetic separation rack?

In step 3 wash and 4 elute above, a magnet is employed. This is where a magnetic separation rack comes into play.

A magnetic separation rack is a tool for magnetic beads enabled sample preparation to provide the magnetic force to pull and aggregate the targeted sample and a tube-holding rack for batch processing.

What makes a good magnetic separation rack?

What makes a good tool? Performance, durability and cost, i.e. effective, rapid, consistent and inexpensive.
In the workflow above, a good magnetic separation rack should be able to pull the targeted sample rapidly and aggregate the sample in a spot that’s easy to perform the aspiration, e.g. close to the tip of the tubes.
NVIGEN’s magnetic separation rack has all these in one, which was originally designed in our lab for our own needs. It’s made of strongest rare earth permanent magnets which provides strongest magnetic force consistently. The magnet is located under the slanted surface snug to the end of the tubes.

NVIGEN's magnetic separation rack

Figure 3. NVIGEN’s in-house magnetic separation rack with 1.5ml tubes and partial zoom-in. The tubes are snug fit to the slanted surface and the sample is aggregated in a tiny spot, leaving room for aspiration.

NVIGEN's magnetic separation rack

Figure 4. NVIGEN’s in-house magnetic separation rack with 0.65ml tubes and partial zoom-in. The sample is aggregated at the tip of the tubes, leaving room for aspiration.

Example: Use NVIGEN Magnetic Rack in DNA extraction

Here is a simple tutorial demonstrating fast DNA extraction and cleanup with NVIGEN MagVigen™ nanoparticles, magnetic rack, magnetic plate and cube magnets.

Compare with other magnetic separation racks

Brand NVIGEN NEB ThermoFisher EpiCypher
Model 16-tube 24-tube 16-tube 16-tube
Picture NVIGEN's magnetic separation rack A20006 NEBNext® Magnetic Separation Rack Invitrogen™ DynaMag™-2 Magnet 12321D Invitrogen™ DynaMag™-2 Magnet 12321D
Price $520 $489 $674 $375
Body Material Aluminum Aluminum No data Aluminum
Magnet Material Strongest rare earth permanent magnets Rare earth magnets No data Strong permanent magnets
Slanted Side Surface Snug fit No Slightly slanted No
Fit Tubes 0.65~2ml 0.2ml 1.5~2ml 0.2ml
Detachable Rack Yes No Yes No

As shown, NVIGEN’s magnetic separation rack is one that’s versatile and cost effective with predictable consistent superior performance.

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