The milling and grinding of samples is an ancient technique that holds applications in a variety of laboratory settings—such as grinding samples for particle characterization or drug preparations in a pharmaceutical laboratory. Anyone who has taken high school chemistry has been exposed to this practice via the humble mortar and pestle. While the mortar and pestle are still widely used by many researchers, demand for instruments that are capable of producing just the right grind—and doing so efficiently and accurately for their process—has caused this laboratory equipment to evolve into a variety of configurations.
Samples—dependent on industry and application, of course—often come in many different types with their own unique physical properties. Samples can be hard or soft, brittle, fibrous or elastic, or even a paste. In light of this, mill and grinder vendors have manufactured specialized products to properly grind any sample for any application. For laboratories working with hard or brittle materials, it is commonplace to see a jaw crusher in use. When working with materials that are soft or fibrous, a cutting mill may be employed.
And then there exists another specialized area of mills and grinders to help speed up the preparation process when working with tissue samples. These units are specialized to ensure that tissue preparation and cell lysis occur seamlessly and without contamination. With the increasing focus on life science applications over the past several years, it’s no wonder that the milling and grinding industry has begun to push into a product area that was once reserved for homogenizers.
When processing sensitive tissue samples, throughput and speed can affect the quality of the sample. Bead mills can accommodate a higher volume of samples than other mill varieties, making them the weapon of choice when working with high volumes of tissue samples. The Bead Mill 24 by Fisher Scientific (Waltham, MA) is capable of accommodating 24 samples simultaneously; this not only allows for greater sample capacity, but also dampens the risk of the tissue samples degrading during the time between runs. Contamination—a common risk in many types of mills—is negated through the use of separate, disposable tubes.
In some cases—especially where extraction of nucleic acids, proteins, or other biochemicals is the main application—a cryogenic solution may be the best choice. Cryogenic grinding equipment comes in a variety of configurations, from traditional mortar-andpestle- style setups to blade mills—such as the Cryogenic Tissue Grinder by BioSpec (Bartlesville, OK). By freezing with dry ice before or during grinding, samples can be made into a powder without altering the biochemical of interest, making for a much smoother extraction process.
In the milling and grinding world, there exist numerous options to choose from, enabling any researcher to find just the right grind for his or her purposes. When it comes to preparing tissue samples, the purchasing landscape is no different. By knowing your samples—and what your end goals are for analysis—finding the right mill or grinder for you can be a straightforward, painless process.
For additional resources on mills and grinders, including useful articles and a list of manufacturers, visit www.labmanager.com/mills-grinders