A centrifuge is equipment that puts the tubes in rotation (spins them in a circle) around a fixed axis. Rotation is caused by the perpendicular force applied to the axis. The force can be powerful. There are many different types of centrifuges, all of which work on the same sedimentation principle.
In molecular laboratories, centrifuges are used to separate two liquids having similar densities or when insoluble particles exist in a solution.
As mentioned earlier, different types of centrifuges work on the same sedimentation principle. The rotor’s acceleration creates a centripetal force to rotate the rotor and centrifuge tubes. Due to this rotation, the high-density substances in the tubes are forced outward in a circular direction while the lighter particles move inwards.
Micro Centrifuge
- As the name explains, these are compactly designed and extremely small in size and, therefore, take up little space on the workbench.
- These are appropriate for use with small tubes (up to 2.0 ml) and often find use in biological procedures.
- These are used for keeping nucleic acids and pelleting proteins from the solutions. They are also used for the microfiltration of minor aqueous samples.
Refrigerated Centrifuge
- This type of centrifuge is used for samples that need to be stored at a lower temperature. They are designed to function at maximum speed and also maintain a consistent temperature.
- They are perfect for analyzing DNA, RNA, PCR, and antibodies. The temperature range is between -20 and -40 degrees Celcius for refrigerated centrifuges.
- According to the need for material, the compartments of refrigerated centrifuges are sealed.
- They offer varying configurations such as swing buckets, fixed angles, or both.
- Materials such as yeast cells, chloroplast, and more sediment swiftly. For them, the refrigerated centrifuge is usually used.
Ultracentrifuge
These centrifuges generate super high acceleration of around 1,000,000 g. They are used to separate molecules with very slight differences, such as proteins and nucleic acids. Ultracentrifuges are further classified into two types;
Preparative Ultracentrifuges
They separate particles based on their different densities. The separation of denser particles for pallet collection and clarification of particles from suspended solutions are the most common uses of preparative ultracentrifuges.
Analytical Ultracentrifuges
They come with an optical detection system that is light-based. It enables the user to do real-time monitoring of the samples as the sedimentation occurs.
Types of Centrifuge Tubes
The samples are kept in tubes in the centrifuges. There can be a variety of centrifuge tubes that can be used. Microtubes that are used for storing minimal amounts of sample, 15 ml tubes, 20 ml tubes, 150 ml or very large 250 ml centrifuge tubes. These standard sizes of centrifuge tubes are used to rotate the samples in a centrifuge.
Colour-coded Centrifuge Tubes
Centrifuge tubes come with different colored caps. These colors are not randomly selected. Instead, every colored cap indicates a different type of sample that has to be kept in it. The color makes it easy for the user to identify which tube to use for what kind of sample. Some standard colors of centrifuge tubes we come across are;
- Purple-capped tubes contain an additive EDTA, which is a coagulating agent. They are usually used to keep blood count samples.
- Yellow-capped tubes contain silica gel and serum gel for separation. These tubes are used to hold liver function and lipid profiling test samples.
- Grey-capped tubes are only used to hold glucose and lactate test samples. They contain two additives that are sodium fluoride and potassium oxalate.
Final Words
Centrifuge and centrifuge tubes are an essential part of any molecular biology. You can not keep the samples fresh without this equipment. Check MBP Inc. to get high-quality products for your laboratory. We have PCR tubes with flat caps, all types of pipettes, storage bottles, Petri dishes, and all other items you need for your lab.
