Test tubes or test tubes are instruments used in all types of laboratories, whether biological, chemical, medicinal, or any other related science. They are used mainly in order to contain liquids and chemicals for later testing or experiments.
Generally, test tubes are made of glass, so that they can withstand all types of environments to which they are exposed. However, there are others made with resistant plastics, which are used for non-abrasive substances or that do not need to be exposed to extreme temperatures.
Index
What is the function of test tubes?
The use of these tools in laboratories can be very beneficial, from the materials and the way they are made, to the possibilities of experimentation with them. Among the benefits offered by the use of test tubes, the following are mentioned:
They have a functional form
These containers have an elongated shape that makes them resistant when handling them, which prevents the liquid contained in the containers from spilling. They are also extremely easy to clean. On the other hand, it should be mentioned that its concave bottom is ideal for transferring the content to another container with minimal liquid waste.
Avoid content contamination
Test tubes are very useful when storing substances or microorganisms that should not have contact with external agents, this due to the shape of their structure, which allows the use of a cap that keeps the test tube sealed.
However, when they are not used they must be sterilized, in this way, when pouring substances, they will remain unaltered in their state.
They allow working with high temperatures
The material from which they are made (usually fused quartz), allows them to withstand high temperatures, which generally exceed 100 degrees C. In addition, given its elongated cylindrical shape, when placed in an inclined position, the content at the bottom is heated while the upper part remains relatively cold, however, they should always be handled with the appropriate tweezers, in order to avoid burns.
They keep chemical reactions under control
Abrasive or corrosive substances do not affect the material from which the test tubes are made. That is why it is possible to control the reactions between the different chemicals, without putting the health of the professional who handles them at risk.
They allow to observe the evolution of the experiments
The test tubes are manufactured with perfectly transparent glasses, in order to make it possible to observe the experiments; for example, the evolution of microorganisms or the reaction between different chemicals.
Test tubes in biology
Culture tubes are the ones used in this science, generally, they are made of resistant plastics and are usually single use, then they are discarded.
They are used to grow any living organism, from bacteria and cells, to plants in their early stages of growth. The shape of these tubes is usually wider, and even totally horizontal to achieve a greater growth surface for the organisms studied.
Test tubes in chemistry
In this area, they are used to contain and transport chemical substances of any kind, including those that may be corrosive or require exposure to high temperatures. For this reason, the strongest test tubes are often used, rather than those made of plastic. In this way, the individual who handles them can be sure that the tube will not break, nor will it yield to any substance that could affect their health.
Experiments in chemistry require test tubes of various sizes and shapes, so the appropriate model must be chosen to ensure that the experiment yields the correct result.
Test tubes in medicine
In medicine it is very important that the tubes are perfectly sterilized, therefore, there are test tubes made specifically for this area, with air removed. These types of tubes are used to collect fluid samples from patients, in order to carry out a study to determine diseases, the cause of their origin or, on the contrary, to rule out any condition and rectify the patient’s health. In addition, they are also used to do the different blood tests, and thus know the body indices of the patients.
Color code on medicinal test tubes
Health professionals use caps of various colors to identify the contents of the tubes more easily. Also, depending on the color, the tube may contain some additive to help with the sample without disturbing it.
- Red cap: Does not contain additives, it is used for serology and clinical chemistry.
- Blue cap: Contains sodium citrate to prevent clotting, used to separate plasma, as well as coagulation and platelet tests.
- Yellow cap: Contains separating gel, it is used for clinical chemistry tests where it is necessary to separate elements.
- Purple cap : Contains EDKA to separate plasma, used in hematology and for blood banks.
- Black cap: Contains sodium citrate, used for erythrocyte sedimentation tests and HSV testing.
- Gray cap: Contains potassium oxalate to prevent glycolysis, is used for liver and glucose tests.
- Green cap: Contains sodium heparin to prevent clotting, used for emergency clinical chemistry and plasma.
- White cap : Contains separator gel and EDKA, used for viral load tests.
Types of test tubes
The model of the test tube should be chosen according to the use to which it will be put. The manufacturing material, shape and size that are most suitable for the work carried out are chosen. Among the most popular types of test tubes, the following should be mentioned:
Plastic test tubes
They are generally made of polypropylene, they are usually disposable, they are used mainly in biology or biochemistry.
Glass test tubes
Their material makes them resistant and easy to keep clean, which is why they are used for all types of chemicals, as well as for clinical tests.
Graduated test tubes
These tubes have marks along their entire length, which indicate the milliliters contained. They are often used in chemical experiments, to accurately measure the amount of the substance to be used.
U-shaped test tubes
It is a U-shaped tube as the name indicates, it is open on both sides and is used for the purpose of comparing the densities of liquids. Two liquids are poured, each one at one end and the one with the highest density will always remain at a lower level, regardless of the amount poured.
Centrifuge and microcentrifuge tubes
They are made of polypropylene and are cylindrical, elongated, with a narrower shape at the bottom, and they also have a built-in lid. They are used in the biochemistry area, for tests that require subjecting substances to centrifugal processes, and thus separating their components.
The smallest ones are usually 1.5 ml, these being the ones suitable for microcentrifuge. Starting at 2 ml, they are considered centrifuge test tubes.
Recommendations for handling
It is important, especially when conducting chemical experiments and processes, to exercise caution in the way the test tubes are handled. That is why it is recommended to take into account the following aspects:
- Use test tube clamps when heating the container, in this way burns are avoided.
- Wear suitable gloves to prevent contact with chemicals or acids that can harm the skin.
- In medicine, use gloves and masks when handling viral samples or contaminants.
- Protect the eyes with suitable lenses against chemical reactions.
- Never direct the opening of the tube directly towards a person, in this way, burns or aspirations of chemical vapors are avoided.
- Use only the first third of the tube, thus avoiding possible spills.
Uses of test tubes outside of laboratories
In addition to all the applications within the laboratories already mentioned, the test tubes are used as decoration pieces in spaces related to science or in environments with innovative decorations.
They are used as vases for small plants, as containers for kitchen spices and also as small lamps. In addition, some use them to preserve memories such as sand the deserts visited. However, its most recent use takes place at parties or discos, where they serve shots of liquor in these small containers.
Conclusion, is it advisable to use test tubes?
Test tubes have been useful tools in various sciences and research centers for several centuries with multiple purposes. Their great versatility has made them participants in the great advances that have been made in biological and chemical matters, such as the discoveries of cures and eradications of serious diseases, since all these events began as experiments in laboratories, inside these small containers, called test tubes.
Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.
