Cryogenic Grinding – Sample Preparation or Milling at Liquid Nitrogen Temperatures
Cryogenic milling or grinding is the solution if you are dealing with tough, flexible or soft samples that are often difficult to grind at ambient temperatures or samples that may temperature sensitive. These types of materials tend to soften, smear or agglomerate during grinding, and do not lend themselves to production of uniform fine powers for analysis.
Cryogenic milling successfully overcomes this problem in many sample types including polymers, biological materials and foodstuffs. By cooling the sample to liquid nitrogen temperatures (-196°C), the sample becomes embrittled. The significant reduction in plastic deformation and their reduced ability to deform under load makes them easier to fracture.
Cryogenic Grinding in DNA/RNA Extraction
Grinding at temperatures less than -80°C is essential for the integrity and longevity of nucleic acids. Negative temperatures prevent the activation of degradation enzymes such as deoxyribonucleases and ribonucleases, therefore preventing the break-down of DNA and RNA and preserving it for future needs and analyses.
SPEX Freezer Mills
How cryogenic grinding works. (Image credit: SPEXUKLTD)
The SPEX Freezer Mill is a programmable laboratory grinder that cools samples to liquid nitrogen temperatures and then pulverises them using a patented horizontal action.
Samples are contained in a sealed vial with a magnetic impactor. The elegant design of the Freezer Mill employs an solenoid to drive the impactor. This means that there are no moving parts subjected to cryogenic temperatures making the system robust, reliable and maintenance free.
The vial consists of a cylinder enclosed at each end by end plugs that the impactor impinges against. The fully enclosed design ensures sample integrity. Vial sets come in a range of sizes and materials to suit sample volumes and types. Similarly, different models are available that cater for different sample volumes and throughput rates.
With an intuitive touchscreen interface, the systems are simple to use. The ability to memorise recipes also adds to their user-friendliness. Typical grinding cycles are of the order of minutes, with the system capable of up to 30 impacts per second.
Applications
- DNA/RNA extraction
- Yeast analysis
- Pharmaceuticals
- Drug testing
- RoHS/WEEE
- Plastic/Polymers/Rubbers
- Food testing
Sample Types
The Freezer Mill is suited to grinding sample types including:
- Animal Tissue including hair, teeth, bone and muscle
- Plant tissue including stems, roots, seeds and leaves
- Polymers
- Yeast
- Pharmaceuticals
- Foodstuffs
- Electronic components
- Textiles
