Centrifuge tubes - Its characteristics, types, and uses

Introduction

A centrifuge tube is a thin, cylindrical tube with a circular bottom and a cover that is used in a laboratory centrifuge machine. Centrifuge tubes, which are composed of plastic or glass, are used to separate materials depending on density. When heavier substances are spun at high speeds in a centrifuge, they settle to the bottom of the tube, while lighter substances remain at the top.

Centrifuge tubes are widely utilized in scientific and medical experiments such as separating blood components, purifying proteins, and isolating DNA. They come in a variety of sizes and can store anything from a few milliliters to several hundred milliliters of liquid.

Centrifuge Tubes Characteristics

There are many characteristics of centrifuge tubes to consider when selecting a suitable tube for a specific application:

Sterility

Some centrifuge tubes are sterile and can be used in sterile conditions, especially while handling biological samples.

Centrifuge Tubes Material

These tubes can be made of either plastic or glass. Plastic tubes are less likely to break and are commonly used for basic laboratory procedures. Glass tubes are more stable and are frequently utilized in more demanding applications such as high-speed centrifugation.

Graduation Marks

Graduation marks are found on some centrifuge tubes and allow the level of liquid in the tube to be easily measured.

Centrifuge Tubes Size

Centrifuge tubes come in a variety of sizes ranging from a few milliliters to several hundred milliliters. It is essential to select a tube that is suitable for the volume of sample being processed as well as the size of the centrifuge being used.

Compatibility with Centrifuge Rotors

It is necessary to select a centrifuge tube that is compatible with the centrifuge machine’s rotor.

Chemical Resistance

Different materials and coatings are used to make centrifuge tubes chemically resistant.

Temperature Resistance

Some centrifuge tubes are manufactured to tolerate extreme heat or cold which makes them suitable for use in a variety of applications.

Size

Centrifuge tubes are normally thin, cylindrical, and have a round bottom.

Centrifuge Tube Types

Centrifuge tubes are classified into three types:

On the basis of size and design
On the basis of materials
Coated centrifuge tubes

Types of Centrifuge Tubes On The Basis Of Size and Design

There are various types of centrifuge tubes used in laboratories and medical settings:

Graduated tubes

These tubes include graduation markers that make it easy to measure the volume of liquid in the tube. They are frequently used to measure and mix liquids.

Micro-centrifuge tubes

These are small tubes that hold a few milliliters of liquid. They are frequently composed of plastic and are commonly utilized in molecular biology and biochemistry experiments.

Cryogenic tubes

These are designed to tolerate cold temperatures and are often used to store and transfer biological samples at low temperatures. They are frequently made of plastic or glass, with a screw cover.

Conical bottom tubes

These tubes contain a pointed bottom, which enables efficient separation of components of a substance. In medical laboratories, they are widely used to separate blood components.

Self-standing tubes

These tubes have a flat bottom and can stand straight without the use of a rack. They are widely used for sample storage and transportation.

Round bottom tubes

Because of their rounded bottoms, these tubes can be spun at high speeds in a centrifuge without spilling. They are frequently used to isolate DNA and purify proteins.

Centrifuge Tubes Types On The Basis Of Material

Centrifuge Tubes Made Of Plastic

These tubes are composed of polypropylene or polyethylene, which are both durable and lightweight materials and also chemical and temperature-resistant. Plastic centrifuge tubes come in a variety of diameters and are often used for basic laboratory procedures. A wide range of raw materials are utilized in the manufacture of plastic centrifuge test tubes, the most common are as follows:

Polypropylene (PP)

These tubes are semi-transparent, chemical, and temperature resistant and can tolerate temperatures below 4°C.

Polystyrene (PS)

These tubes are transparent, hard, and disposable.

Polycarbonate (PC)

These tubes are transparent. They are hard and resistant to high temperatures. Do not use them for strong acids, strong alkali, and alcohol.

Polyamide (PA)

These tubes are translucent and have stronger chemical stability, but cannot be used at high temperatures.

Cannot be used at elevated temperatures

Polyflouride (PF)

These tubes are translucent and can be used at low-temperature i.e. -140℃ to -100℃.

Polyethylene (PE)

Opaque

These are opaque. They are not reactive for hydrochloric acid, acetic acid and acetone. They can be soft when used at high temperatures.

Cellulose acetate butyrate (CAB)

These tubes are transparent and can be used for gradient determination for dilute acids, alcohol, salts, alkali and sucrose.

Figure 1: centrifuge tubes made of plastic (Stemmer et al. 2013)

Centrifuge Tubes Made Of Glass

Glass centrifuge test tubes are another option to be use. SiO2, NA2B4O7, H3BO3, 10H2O, CaO, Na2O, glass cullet, P2O5 and different oxidizing chemicals such as potassium, magnesium, zinc, and aluminum are among the raw components of glass.
These tubes are made of borosilicate glass, which is resistant to both heat shock and chemical attack.
The majority of glass centrifuge test tubes are chemically resistant, allowing them to be used with tested substances such as water, salt solutions, acids, bases, and organic solvents. So these test tubes are more useful than plastic centrifuge test tubes. Only hydrofluoric acid, strong bases, or concentrated phosphoric acid will destroy glass when heated.
Because glass centrifuge tubes are stronger and chemically resistant than plastic tubes, they are generally used for more demanding experiments such as high-speed centrifugation or the storage of hazardous materials. Glass centrifuge tubes come in a variety of diameters and with either a screw top or a snap cap.

Figure 2: glass centrifuge tubes of 100ml volume capacity (Raynel et al. 2021)

Coated Centrifuge Tubes

Some centrifuge tubes have a layer of plastic or another material put on them to make them more resistant to certain chemicals or to increase their performance in specific experiments.
Coated centrifuge tubes come in a variety of sizes and can be made of plastic or glass.

Figure 3: silica coated centrifuge tube (Afat et al. 2019)

Centrifuge Tubes Cap Types

Screw caps

These caps are typically used for tubes that are preserved or exported because they provide a secure seal. They are also widely utilized for high-speed centrifugation or hazardous substance storage. Screw caps can be purchased in a variety of sizes and materials, such as plastic and metal.

Snap caps

These caps are easier to open and close, and they are typically used for tubes that are frequently used during laboratory experiments. They can be found in a variety of sizes and materials, including plastic and metal.

Screw caps and snap caps come in a variety of colors that can be used to mark and identify various samples or solutions. Some centrifuge tubes contain a cap with a built-in sealing gasket, which adds an extra layer of leak protection.

Sizes of Centrifuge Tubes

Centrifugal tubes typically have capacities ranging from a few milliliters to 100 milliliters. Centrifuge test tubes are classified according to their capacity such as; large-capacity centrifuge test tubes, small-capacity centrifuge test tubes, or micro centrifuge test tubes.

Large-capacity centrifuge test tubes are often known as centrifuge vials or centrifuge bottles. Its volume typically ranges from 250ml to 500ml.
The most typical centrifuge test tube capacities are 15 ml and 50 ml.
Microcentrifuge test tubes typically have capacities of 0.2ml, 0.65ml, 1.5ml, and 2ml. 1.5 ml microcentrifuge test tubes are the most commonly used tubes in laboratories.

Figure 4: centrifuge tubes of different volume capacities (Chandrasekhar and Gireesh 2008)

Applications of Centrifuge Tubes

In medical laboratories, conical bottom tubes are widely used to separate blood components such as red blood cells, white blood cells, and plasma.
Micro centrifuge tubes are widely used in molecular biology and biochemistry experiments such as nucleic acid separation and enzyme purification.
Round bottom tubes are often used for centrifugal protein purification. These tubes are also often used for centrifugation-based DNA isolation.
Centrifuge tubes are often used to prepare samples for examination by separating the sample components based on density. Toxins are often extracted from biological materials using centrifuge tubes.
Graduated tubes are frequently used to measure and mix liquids.
For storing and transferring samples, self-standing tubes and cryogenic tubes are often utilized.
Because they are strong and chemically resistant, glass centrifuge tubes with screw covers are often employed for hazardous material storage.

Advantages of Centrifuge Tubes

When compared to other separation procedures, centrifuge tubes allow for the effective separation of substances depending on their density, which can save time and resources.
Centrifuge tubes come in a variety of diameters and materials, making them useful for a wide range of applications.
Centrifuge tubes are simple to use and do not require any extra equipment or training. These tubes are simple to store and carry, making them useful in a number of experimental procedures.
Centrifuge tubes are a cost-effective means to separate compounds in a laboratory or medical setting.
Centrifuge tubes enable precise separation of substances based on density, which is vital for many scientific and medical applications.
Some centrifuge tubes are sterile and can be used to process biological samples.

Disadvantages of Centrifuge Tubes

If centrifuge tubes are not sealed properly or are damaged, they can leak.
They might not be useful for processing large quantities of sample.
It is essential to use a centrifuge tube that is compatible with the rotor of the centrifuge.
When measuring small volumes of liquid, graduated tubes may not be 100% precise.
If these are discarded after a single usage, they may generate waste, which can be hazardous to the environment.
There is a risk of contamination of the sample being processed if reusable tubes are not thoroughly sterilized.
There is a chance that user harm, if a centrifuge tube breaks or leaks.
Centrifuge tubes may not be suitable for all sorts of separations or samples.

Precautions while Handling Centrifuge Tubes

It is vital to select a centrifuge tube that is appropriate for the volume of sample being processed.
When using the centrifuge tubes, it is essential to follow the manufacturer’s recommendations.
When working with hazardous materials in a centrifuge, it is critical to use adequate personal protective equipment, such as gloves and safety glasses.
To prevent leaks and spills, ensure that the tubes are tightly closed and properly sealed.
If a centrifuge tube breaks, handle the cracked parts with care to avoid cuts or other injuries.
If reusable tubes are used, it is essential to sterilize them well between uses to avoid infection.
Properly dispose of centrifuge tubes.

Top Centrifuge Tubes Manufacturing Companies

Thermo Fisher Scientific.
Corning.
Eppendorf
VWR:
Sigma-Aldrich:

What Points You Should Keep In Mind While Purchasing Centrifuge Tubes?

Because pricing can vary depending on RCF value, you should first estimate the RCF required for your workflow before looking for tubes that can withstand these forces.
You should constantly check their chemical resistance to see if they are suitable for your technique.
The ability of centrifuge tubes to autoclave is also affected by their composition. Glass, PP, and PA tubes are commonly autoclaveable, whereas PET tubes are not. PC tubes can be autoclaved.
The sample volume determines the best tube size. Keep in mind the sample volume you want to frequently work on.
Another component of centrifuge is the sealing mechanism of your tubes. Purchase tubes with suitable caps for your workflow.

References

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Chandrasekhar T, Gireesh TJJORR-KL-RRIOM-. 2008. Latex as yield may be better than rubber yield in juvenile screening for selection in rubber (Hevea brasiliensis Muell. Arg.). 11(1): 52.
Raynel G, Marques DS, Al-Khabaz S, Al-Thabet M, Oshinowo LJO, Science G, nouvelles TRdIE. 2021. A new method to select demulsifiers and optimize dosage at wet crude oil separation facilities. 76: 19.
Stemmer K, Burghardt I, Mayer C, Reinicke GB, Wägele H, Tollrian R, Leese FJOD, Evolution. 2013. Morphological and genetic analyses of xeniid soft coral diversity (Octocorallia; Alcyonacea). 13: 135-150.