Homogenizers are used to disperse, emulsify, lyse, or mill samples as diverse as tissue, soil, and cosmetics. Although a simple mortar and pestle can accomplish somewhat similar results, a high level of consistency can be achieved only by a mechanical homogenizer with a decent generator probe. To get the most out of a lab homogenizer, it is crucial to select the right features for given applications and to maintain it properly.
Picking your unit
Homogenizers come in a variety of configurations, including handheld and bench-mounted models with a variety of probes to match the correct sample type. The primary selection criterion for a homogenizer is the sample or material type being processed.
The wattage required will depend on both the sample type being processed and the size of the samples. Processing small volumes requires less power, so a handheld unit is usually the best choice in these cases. But to homogenize a large volume of viscous material, a larger motor may be needed. Certain homogenizer units are capable of processing a wide range of sample volumes, from milliliters to liters.
In many cases, the speed of the process matters as well. For example, faster processing time increases the quality of the yield for nucleic acids and proteins because it gets them into the protective buffer faster. Speed controls are available in some mechanical units to enable the user to adjust the speed in increments of hundreds of RPM.
The friction generated by a homogenizer will cause an increase in temperature during operation. The simplest way to reduce the effect of temperature on the samples is to select the correct generator probe and unit for your application, which will decrease the time spent homogenizing the sample, thus reducing the effect of temperature. Many manufacturers, including those of blender-style homogenizers, have also begun creating builtin cooling systems to combat temperature increases. Here are some of the most important features to look for when purchasing a homogenizer:
- Easy cleaning of product-contact surfaces
- A low motor noise, since homogenizers are usually located on workbenches in proximity to operators
- Ease of use
- Rapid homogenization
- User control over homogenization parameters through a familiar digital display
- Low heat generation, which is particularly important for labile tissue samples
- A programmable library of methods
Maintenance is key
Once a homogenizer has been selected and purchased, the next challenge is to keep it in good condition. The life of a probe-based homogenizer can be extended with some simple care of the generator probe—the part that actually goes into the sample. Although some homogenizers do not have a generator that can be easily taken apart, purchasing a system that allows for a thorough cleaning once in a while is generally considered a better investment.
The upper and lower bearings need to be replaced on a semiregular basis; the specific replacement time depends on use. While a new generator probe can run more than $1,000, a pack of bearings costs a mere $30 to $40. Thus, small repairs can provide a substantial return on investment in the long run.
Signs that it’s time to perform maintenance on your homogenizer include the sample heating up, the generator probe or motor unit becoming hot to the touch, or black residue appearing in your sample. Wearing or discoloration on the internal components, such as PTFE bearings, or your generator probe seizing up are also signs that it’s time for service. Additionally, if the generator probe has never been taken apart for a cleaning, then chances are that some maintenance is required.
For additional information on homogenizers, including useful articles and a list of manufacturers, visit www.labmanager.com/homogenizers
