What are the features you should look for when choosing microcentrifuge? It depends on your lab's particular uses. Some of the basic considerations in making this important decision include...
What is a Microcentrifuge?
A microcentrifuge is a tabletop laboratory appliance used to apply centrifugal force to small amounts of liquid up to two milliliters. It is sometimes called a microfuge. Centrifugal force is applied in order to separate a solid
Using a Microcentrifuge
from the liquid it is suspended in. The liquid is placed in microcentrifuge tubes before being placed in the unit. The tubes must be the right size for the microcentrifuge you are using.
Every laboratory needs a good centrifuge and the appropriate accessories.
What are the features you should look for when choosing one? It depends on your lab’s particular uses.
Some of the basic considerations in making this important decision include the capacity, the speed, and the size of the unit. Also, do you need a unit that has the capacity to control the temperature of the sample and, for instance, keep it refrigerated while it is spun?
The tubes used in microcentrifuges come in different sizes, such as 0.5 ml. or 1.5 ml. The microcentrifuge will be designed for one size of tube, but you can use an adapter if you need to use a smaller tube, so choose the unit that will be able to handle the largest sized tubes you will be working with. Some microfuges have different sized slots in the rotor so they can handle different sizes of tubes. Some have adapters that permit the rotor to handle different sized tubes.
Other things to consider before purchasing and operating tips…
- Consider also how many samples you will be needing to run at the same time. Inside the microcentrifuge is a rotor with spaces for the tubes. The number of spaces varies from 6 to 24 or more. You can always do fewer than capacity, but if the unit you choose does not have room for the volume of testing you need to do, it will be frustrating. More simply put, you can use a larger unit with fewer microcentrifuge tubes, so look for the largest capacity you think you may need.
Do remember to counter-balance your tubes when you use it. In other words, if you are processing a microfuge tube with one milliliter of sample, you must place another tube with one milliliter of water in the rotor directly opposite of your sample. In microfuges designed for several sizes of tubes, you may need to counter balance with two other samples in a triangular format. Make sure the tube lids are closed securely.Place the rotor lid on the rotor securely. Replacing this safety lid each time the unit is used is very important to the maintenance of the microfuge. On some units, this safety lid has a central screw that must be tightened before use. The rotor lid may be made of plastic or metal. Transparent plastic lids are nice because you can see if there is a broken tube in the rotor before you open it up. Metal lids tend to be more durable over the long run. Some microfuge units are designed without a rotor lid. For these, you simply lower the microfuge cover to use.
- Each microcentrifuge can be adjusted for time and speed. The various models differ in how this is done. Some have up and down arrow buttons and a digital readout. Others have knobs that turn to specific settings.
To place the exact small amount of sample into the tube requires the use of a micropipette. This instrument draws up liquid in much the same way as an eye-dropper, but is capable of precisely measuring the liquid. A micropipette is also useful for removing the liquid supernate from the tube in order to access your precipitate, or “pellet” in the bottom of the tube.
Needed Accessories… Micropipettes
Micropipettes come in different sizes. Each is labeled in microliters according to the top of the volume range that it will measure. They should never be used on samples of a size outside of their range. For example, a P200 micropipette can hold from 20 to 200 microliters. For smaller or larger samples, you will need a smaller or larger micropipette.You can adjust the volume you wish to pipette by turning dials on the micropipette. At this time, you will need to attach the appropriate disposable pipette tip. If you wish to filter the liquid you will be drawing up, you can use a filter tip. You will need a new, clean tip for each use.
Here is a summary of things to think about when choosing microcentrifuges, micropipettes, and microfuge tubes.
- What size of individual samples will you be centrifuging?
- How many tubes will you need to be able to do at a time?
- Do you need refrigeration or will a plain model be adequate for your needs?
- Will you be spinning hazardous materials? If so, be sure to choose a unit with a safety lid on the rotor.
- What sizes of samples will you need to pipette? You may need several sizes of micropipettes.
- Make sure you get enough tips in the right size and style, too.
For microcentrifuge tubes, first consider the size you need. Make sure it is a size you can use in the microfuge you select. Some high quality tubes stay closed when submersed in boiling water and won’t pop open or crack when used in the freezer. The lid should be designed with a writing surface on the top if you will be labeling them with a permanent marker.
I hope this helps you choose the right microcentrifuge for your needs.