Chemists frequently utilize test tubes to hold, combine, or heat small amounts of solid or liquid compounds, particularly in qualitative studies and assays. They are easier to clean, have a round bottom and straight sides that reduce mass loss when pouring, and enable convenient contents monitoring.
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What is Test Tube?
A test tube, also known as a culture tube or sample tube, is a common chemistry lab glassware made of a finger-length of clear plastic tubing that is open at the top and has a rounded U-shaped bottom.
Michael Faraday, a well-known British physicist and chemist, designed the test tube (1791-1867).
Test tubes are small tubes used in laboratories to mix or heat substances. They are often made of glass or plastic, with an open top and a rounded bottom. Some are designed to be reused, while others are meant to be thrown. Test tubes are a type of labware that is also known as culture or sample tubes, depending on their application. Common test tube materials include glass, plastic, metal, and ceramic. The most popular materials are glass and plastic; some are designed for reuse, while others are disposable.
Types of Test Tubes
Test tubes are classed according to a variety of factors, including size, material, and particular purposes. Here are a few classifications:
On the Basis of Size
Test tubes vary in size, from very small (microcentrifuge tubes) to larger tubes used for bulk storage or mixing.
Microcentrifuge Tubes: These are extremely small tubes designed for microscale applications.
Capacity typically ranges from a few hundred microliters to a few of milliliters.
Small Test Tubes: Diameter is approximately 10-16 mm. Length: Shorter lengths are commonly employed for small-scale reactions and storage.
Medium Test Tubes: Diameter: Approximately 16-20 mm. Length: Moderate lengths are suited for a wide range of typical laboratory applications.
Large Test Tubes: Diameter: 20 mm and above. Length: Longer lengths are commonly utilized for larger-scale reactions, storage, and mixing.
Macro Test Tubes: These are even larger tubes designed for large quantities. Diameters and lengths can vary greatly.
On the Basis of Materials
Glass Test Tubes: Traditional, typically reused which is made of borosilicate glass or soda-lime glass. Theses are especially suitable for general laboratory applications. Heat and most chemicals do not harm it. These can be sterilized using an autoclave.
Plastic Test Tubes: Disposable and made of various plastics, such as polypropylene and polystyrene. These are lightweight and break-resistant. They are ideal for applications that require disposability or have a significant risk of breakage. These tubes are frequently used in clinical and molecular biology settings. Some plastic tubes are autoclavable, however most are intended for single use.
Quartz or Borosilicate Glass Tubes: Used in specific applications that demand strong heat resistance or chemical inertness. Quartz glass is UV transparent, making it ideal for certain analytical methods. Borosilicate glass is also resistant to thermal shocks.
Silicone-coated Tubes: Tubes with silicone coating to improve sample recovery by lowering surface tension. Useful in situations that require optimum liquid sample recovery.
Cryo Tubes: Tubes used to store samples at extremely low temperatures, often composed of specialist materials that can endure severe cold, such as polypropylene.
Gas Collector Tubes: Made from materials that can gather gasses without absorbing or reacting.
Light-sensitive Tubes: Amber or dark-colored tubes are used to protect light-sensitive materials from deterioration. These tubes are commonly constructed of glass or plastic.
Based on Applications
Reaction Tubes: Used to mix reagents and perform small-scale chemical reactions. Available in a variety of sizes and materials to accommodate varying reaction circumstances.
Storage Tubes: Designed to safely store liquids or samples. There may be secure closures to prevent evaporation or contamination.
Sample Tubes: Used to gather and transport samples from one site to another. Often disposable to avoid cross-contamination between samples.
Measuring Tubes: Graduated tubes are meant to provide precise volume readings.
Commonly used in titrations and other quantitative tests.
Heat Tubes: Suitable for applications that need the application of heat. Made of materials that can tolerate extreme temperatures without breaking.
Freezing Tubes: Designed to store samples at extremely low temperatures, typically in freezers or cryogenic conditions.
Centrifugal Tubes: Specifically developed to endure high centrifugal forces throughout the centrifugation process. Conical bottoms may be used to separate components more efficiently.
Biological Tubes: Used in biological applications like cell culture and microbiological research.
Frequently have characteristics that facilitate aseptic methods.
PCR Tubes: Designed specifically for polymerase chain reaction (PCR) applications.
Made using materials that can be thermally cycled.
Blood Collection Tubes: Designed to collect, store, and transport blood samples. Depending on the purpose of the analysis, different additives or anticoagulants may be used.
Disposable vs Reusable Test Tubes
Disposable test tubes are constructed from a variety of plastics, including nylon, polyethylene, polypropylene, polyurethane, polyvinyl chloride, and polytetrafluoroethylene. Plastic test tubes, like neoprene tubes, are resistant to UV light and can operate in temperatures ranging from -30℉ to 275℉. Polyethylene plastic tubes can withstand high pressures.
Reusable test tubes are composed of glass, including borosilicate, fused silica, and quartz glass. These tubes are highly temperature resistant, autoclavable, and chemically tolerant. Despite being clear, these tubes are more expensive than disposable ones.
| Disposable Test Tube | Reusable Test Tube |
| Disposable tubes are ideal for single use and eliminate the need for cleaning and sterilization. | Reusable tubes can be autoclaved for sterilization, ensuring that they are free of contaminants before each use. Suitable for applications where sterility is required. |
| Disposable tubes eliminate the possibility of cross-contamination among different samples. Particularly significant in applications requiring high sample purity. | Reusable tubes generate less environmental waste, making them a more sustainable option. Laboratories with an emphasis on sustainability may favor reused materials. |
| Disposable choices could be less expensive than buying a lot of reusable tubes for experiments that need a lot of tubes. | While the initial investment may be costlier, reusable tubes can become more cost-effective over time, particularly in applications where they will be used repeatedly. |
| Laboratories do not have to spend resources for washing, autoclaving, and maintaining disposable tubes. | Reusable tubes are frequently more versatile, ideal for a variety of applications beyond basic storage, such as chemical reactions. |
Use of Test Tubes
Test tubes serve a variety of purposes depending on the laboratory. These tubes are used in chemical laboratories to examine the properties of substances and to conduct experiments with two or more compounds in various forms. The different functions of test tubes are as follows:
Sample collection in clinical laboratories: Clean, sterilized test tubes are used to collect samples such as body fluids (saliva, pus, and sputum). It allows for the efficient movement of samples from one location to another in order to confirm disease diagnosis.
Mixing and storing reagents: Test tubes are frequently used to mix and store small amounts of liquid chemicals used in chemical processes. They provide a regulated environment in which reactions can occur.
Heating and boiling: Heat-resistant test tubes, often composed of borosilicate glass, are used to heat and boil liquids. They are appropriate for applications that demand controlled temperature conditions.
Blood collection: Blood collection tubes are test tubes with color-coded tops that aid in determining the purpose of the blood collection and any preservatives applied to the tube.
Culturing microorganisms: Culture tubes, a type of test tube, are used to grow and maintain bacterial, yeast, or other cell cultures under controlled conditions.
Chemical analysis: In a chemistry lab, a test tube is useful for studying substances. Multiple test tubes are used to study the physical and chemical properties of compounds in various physical states (solid, liquid, and gas).
Disease diagnosis: The use of test tubes in clinical and microbiological laboratories not only aids in the collection of samples and blood, but also in disease diagnosis through the performance of numerous tests, particularly cancer cell culture and biochemistry testing.
Disadvantages of Test Tubes
Limited Volume: Test tubes have lesser capacities than flasks, which can be a disadvantage when bigger reaction amounts are needed. It may be difficult to scale up processes or conduct studies that require bigger amounts of reagents or samples.
Heat Transfer: Test tubes are less effective in transferring and distributing heat than flasks. This constraint can be significant for reactions requiring precise temperature control or when using heating equipment.
Lack of Stability: Test tubes have a thinner base and are more prone to tipping over, especially when employed in complex setups or when vigorous mixing is necessary. This can result in spills, breakages, and the loss of valuable samples.
References
- https://microbeonline.com/test-tube-types-uses-and-importance/
- https://www.superfitcare.com/What-Are-the-Different-Types-of-Laboratory-Test-Tubes-id3412389.html
- https://www.heger.no/testing-tubes
- https://themasterchemistry.com/test-tube-working-types-and-uses/
- https://www.labkafe.com/blog/test-tubes-1221
- https://www.globalspec.com/learnmore/labware_scientific_instruments/clinical_research_labware/test_tubes
- https://microbiologynote.com/test-tube/
