Laboratory Test Tube - Types, Limitations, Advantages, Uses

Test tube is a simple laboratory glassware which is used in different laboratory works. It is a cylindrical tube like container, open at one end and closed at the other end. It is also called culture tube or sample tube.

It is generally long and narrow in shape. The lower end may be rounded, flat or conical. The upper open end may be plain, flared or sometimes threaded for fitting a cap.

Test tube is commonly made up of glass or clear plastic. Glass test tube is usually made from borosilicate glass because it can tolerate heat and chemicals. Plastic test tube is made from polypropylene or polystyrene and it is used for normal holding and sample work.

The size of a test tube is usually about 10 to 20 cm in length and 1 to 2 cm in width. It is used to hold small quantity of liquid, solid or biological sample. Blood, urine, culture medium and chemical solution can be kept in it.

Test tube is used in chemistry, biology and medical laboratory. It is used for mixing, heating, storing and observing small amount of substances. Its transparent wall helps to see colour change, reaction and growth clearly.

Types of test tubes

Different types of test tubes are as follows-

Standard test tube
It is the common test tube used in laboratory. It is used to hold, mix, heat and observe chemical or biological liquid substances. It may have flat bottom or rounded bottom.
Boiling tube
It is a large and wide test tube. It is made up of thick glass. It is used for boiling liquid substances strongly without easy splashing.
Ignition tube
It is a small thick-walled tube. It is made up of borosilicate glass. It is used for strong heating of small amount of solid powder over flame.

Centrifuge tube
It is a tube with tapered or conical bottom. It is used in centrifuge machine. It helps in separation of solid and liquid components at high speed.
NMR tube
It is a very thin glass tube. It is used to hold liquid sample for Nuclear Magnetic Resonance study. It is used in NMR spectrometer.
Thiele tube
It is a glass tube with triangular side arm. It is used for uniform heating of oil bath by convection current. It is used to determine melting point and boiling point.

Thistle tube
It has a thin shaft with reservoir and funnel-like opening at upper end. It is used to add liquid into another apparatus. It helps to add precise amount of liquid.
Nessler tube
It is a standardized flat-bottom glass tube. It is used to compare colour and turbidity of liquid sample. It is used with standard solution.
Schlenk tube
It is a special reaction tube with side arm and stopcock valve. It is used for air-sensitive and moisture-sensitive compounds. It is connected with vacuum or inert gas system.

Culture tube
It is a clear tube used in microbiology. It is used to culture and grow bacteria, fungi and other organisms. It may have screw cap for sterile condition.
Cryovial tube
It is a temperature-resistant tube. It is used for freezing and storing biological samples. It is used at very low temperature.
PCR tube
It is a small thin-walled polypropylene tube. It is used in PCR process. It allows rapid heating and cooling for DNA amplification.

Vacutainer tube
It is an evacuated clinical sample collection tube. It is used to collect and transport blood and other physiological fluids. It has different coloured caps according to the additive present inside.

Types of vacutainer tube are-

Lavender or purple-top tube
It contains EDTA. It is used for whole blood hematology test such as complete blood count (CBC).
Light blue-top tube
It contains sodium citrate. It is used for blood coagulation studies.

Green-top tube
It contains heparin. It is used for plasma chemistry testing.
Gray-top tube
It contains sodium fluoride and potassium oxalate. It is used for blood sugar testing.
Red-top tube
It contains no additive or silica clot activator. It is used for serum separation for diagnostic chemistry and serology tests.

Gold-top tube
It contains clot activator and barrier gel. It is used to separate serum from blood cells.

Material Used for Test Tube

Different materials are used for making test tube according to its laboratory use. The following are the important materials used for test tube-

Glass– Glass is the most common material used for making test tube. It may be borosilicate glass or soda-lime glass. Borosilicate glass can resist heat and sudden temperature change, so it is used for heating and chemical work.

Plastic– Plastic test tube is made up of clear synthetic polymers. Polypropylene, polystyrene and polyethylene are commonly used plastics. These tubes are light, disposable and do not break easily.
Quartz– Quartz is used for special type of test tube. It allows ultraviolet light to pass through it. It is used in special laboratory works where UV transparency is required.
Metal– Metal test tube is used in some special laboratory condition. It is strong and can tolerate high temperature. It is not transparent, so it is not used for observing colour change.

Ceramic– Ceramic test tube is used where strong heating is required. It can tolerate high temperature and chemical action. It is used for special heating and ignition type work.

Laboratory Tube Collection Based on Color

Different laboratory tubes are identified by the colour of the cap. The colour indicates the additive present inside the tube and its use. The following are the important laboratory tube collection based on color-

Red-top tube– It contains no additive or silica clot activator. It allows the blood to clot naturally. It is used for blood typing, hormone test, toxicology and other tests where serum is required.

Gold-top or tiger-top tube– It contains clot activator and separator gel. It is used for serum testing. It is used in blood chemistry, metabolic panel, thyroid function test and lipid profile.
Light blue-top tube– It contains sodium citrate. It acts as anticoagulant by binding with calcium. It is used for coagulation studies such as prothrombin time (PT), activated partial thromboplastin time (aPTT) and INR.
Lavender or purple-top tube– It contains EDTA as anticoagulant. It prevents clotting and preserves the shape of blood cells. It is used for hematology tests like complete blood count (CBC), blood smear and HbA1c.

Green-top tube– It contains heparin, either sodium heparin or lithium heparin. It prevents coagulation of blood. It is used for plasma chemistry test such as cholesterol, ammonia, insulin and also cytogenetic studies.
Gray-top tube– It contains sodium fluoride and anticoagulant such as potassium oxalate or heparin. Sodium fluoride prevents breakdown of glucose by cells. It is used for blood sugar test and lactic acid test.
Yellow-top tube– It contains SPS or ACD. SPS means Sodium Polyanethol Sulfonate and ACD means Acid Citrate Dextrose. It is used for blood culture test, DNA studies and tissue typing.

Pink-top tube– It contains EDTA as anticoagulant. It is mainly used in blood bank procedures. It is used for blood typing, antibody screening and crossmatching before transfusion.
Black-top tube– It contains sodium citrate as anticoagulant. It is used for erythrocyte sedimentation rate (ESR) test. This test measures how fast red blood cells settle and helps to detect inflammation.

Limitations of test tube

The following are the limitations of test tube-

Narrow shape- Test tube has narrow and long shape. During heating, liquid may boil suddenly and violently. This is called bumping and it can throw the liquid out from the tube.

Breakage of glass- Glass test tube can break or crack easily. It may shatter when it falls down or hit with hard surface. Broken glass can cause injury in laboratory.
Thermal stress -Glass test tube needs slow and uniform heating. Sudden heating or sudden cooling can produce thermal stress. Due to this, the tube may crack or break during experiment.
High maintenance- Reusable glass test tube needs proper washing and sterilization. It requires water, energy and heating equipment. So, maintenance of glass test tube may increase laboratory cost.

Plastic contamination- Plastic test tube may release some chemicals from its material. These chemicals may mix with biological sample. It can affect test result, enzyme activity and optical reading.
Heat sensitivity of plastic- Plastic test tube cannot tolerate high temperature. It may bend or deform during strong heating. So, it is not suitable for boiling and direct flame heating.
Chemical sensitivity of plastic- Plastic test tube is less resistant to strong solvent and concentrated acid. Some chemicals can damage the plastic wall. It may affect the sample and the experiment.

Permeability of plastic- Some plastic tubes allow gas or moisture to pass through it. They may also absorb some reagents. This can change the quality and concentration of the sample.
Degradation of plastic- Plastic test tube is not always useful for long time. It can become brittle or cracked after repeated use. So, it is mostly used as disposable tube.
Environmental problem- Plastic test tubes are often single-use tubes. They produce large amount of plastic waste. Their production and disposal also create environmental burden.

Advantages of test tube

The following are the advantages of test tube-

Easy handling- Test tube is easy to handle in laboratory. It is used to hold, mix and heat small amount of liquid or solid substance. It can be easily kept in test tube rack.
Simple design- It has simple cylindrical shape. Its vertical side and rounded bottom helps in proper mixing of substances. It also reduces loss of material during pouring.
Less spilling- Test tube has narrow mouth. So, the chance of spilling is less during handling. It is useful while working with harmful chemicals and small amount of sample.

Clear observation- Test tube is generally made up of transparent glass or plastic. So, the content inside the tube can be seen clearly. Colour change, precipitation, gas formation and growth can be observed easily.
Heat resistance- Glass test tube can tolerate high temperature. It is used for heating chemicals directly or indirectly. Borosilicate glass test tube is more suitable for heat and chemical work.
Chemical resistance- Glass test tube does not react with most chemicals easily. So, it is useful for testing acids, bases and other reagents. It helps to carry out reaction safely.

Safe and convenient- Plastic test tube is light in weight and does not break easily. It is useful for disposable work. It reduces injury from broken glass and also reduces contamination.
Small sample requirement- Test tube is used for small amount of sample. So, less chemical and less biological material is required. This makes laboratory work simple and economical.

Uses of Test Tubes

The following are the uses of test tube-

Holding of substances- Test tube is used to hold small amount of liquid or solid substances. Chemicals, reagents and biological samples can be kept in it during laboratory work.

Mixing of chemicals- It is used for mixing small amount of chemicals. The substances can be mixed by shaking the tube gently. It is useful for simple chemical reaction and testing.
Observation of reaction- Test tube is used to observe chemical reaction clearly. Colour change, gas formation, precipitation and other changes can be seen through the transparent wall.
Heating and boiling- Glass test tube is used for heating small quantity of liquid or solid powder. It can be heated directly over Bunsen burner or by using water bath. Boiling tube is used when strong boiling is needed.

Sample collection and storage- Test tube is used for collection and storage of clinical sample. Blood, urine, pus and synovial fluid can be collected in it. The sample may be stored for further analysis.
Centrifugation- Special conical test tubes are used in centrifuge machine. It helps to separate substances of different density. Cells, proteins and nucleic acids can be separated by high speed spinning.
Microbial culture- Test tube is used in microbiology for growing microorganisms. Bacteria, fungi and molds can be cultured in it. It is also used for maintaining culture under sterile condition.

Measurement of liquid- Graduated test tube has markings on its wall. It is used to measure small volume of liquid. It helps to take required amount of sample during experiment.
Collection of gases- Test tube is used for collection of gases in laboratory. An inverted test tube is placed in water to collect escaping gas. It is commonly used during electrolysis and gas preparation.
Transportation of sample- Test tube with cap is used for transporting sample from one place to another. It helps to prevent leakage and contamination. It is useful in field work and clinical laboratory.

Alternative use- Test tube is sometimes used outside laboratory also. It may be used as small flower vase, spice container, shot glass or for keeping small living organisms.

References

Machined Quartz. (2021, April 1). 6 Types of tubes used in science laboratories.
Thomas Scientific. (n.d.). APHA Nessler color comparisons tubes with cap stoppers.

Green Science Policy Institute. (n.d.). Bisphenols & phthalates.
ChemScience. (n.d.). Borosilicate glass vs soda lime glass: Understanding the differences.
Harris, A. (n.d.). Choosing between glass and plastic test tubes in phlebotomy: Advantages, considerations, and recommendations. Needle.Tube.
Fisher Scientific. (n.d.). Color comparison tubes.
Ferrara, C., & De Feo, G. (2023). Comparative life cycle assessment of two different packaging systems for extra-virgin olive oil: Glass bottle vs. 100% recycled polyethylene terephthalate (PET) bottle. Sustainability, 15(4), 3665.

Verive & Bunzl Catering Supplies. (n.d.). Comparing carbon footprints: Disposables vs reusables.
Comprehensive scientific analysis of laboratory test tubes: Material engineering, analytical specialization, and clinical systematics. (n.d.).
Advanced Technical Products Supply Co. (2021, February 1). Soda lime glass vs. borosilicate glass – What’s the difference?

Aly, M. (2025, February 16). Environmental impact of drinking cups: Plastic vs glass – A life cycle assessment perspective. EmVide.
DWK Life Sciences. (n.d.). Glass types & properties.
ChemScience. (n.d.). Glass and plastic test tubes: A comprehensive comparison.
Analitika Expo. (n.d.). Glass vs plastic labware: Choosing the best for your lab.

Lab Manager. (n.d.). How tubes can affect your experiments.
Lewis, L. K., Robson, M., Vecherkina, Y., Ji, C., & Beall, G. (2010). Interference with spectrophotometric analysis of nucleic acids and proteins by leaching of chemicals from plastic tubes. Biotechniques, 48(4), 297–302.
Simple Business Help LLC. (2021, April 16). Laboratory glass tubes: Differences of common laboratory glassware tubes. Lab Pro Inc.
Laboratory plasticware induces expression of a bacterial virulence factor. (n.d.). PubMed Central (PMC).

Yelimeshyn, S. (2025, December 24). Laboratory plasticware vs. glassware: Pros, cons, and best uses. BostonMed Supply.
Al-Taie, A. J. (n.d.). Laboratory test tubes. Al Mustaqbal University.
Leaching of phthalates from medical supplies and their implications for exposure. (n.d.). PubMed Central (PMC).

Ayumi. (2026, February 6). Medical lab tubes explained: Types by color, additives, uses, and proper handling. Global Pharma.
Pobel. (n.d.). Nessler tubes.
Pobel. (n.d.). Nitrogen or Schlenk tubes.
Olivieri, A., Degenhardt, O. S., McDonald, G. R., Narang, D., Paulsen, I. M., Kozuska, J. L., & Holt, A. (2012). On the disruption of biochemical and biological assays by chemicals leaching from disposable laboratory plasticware. Canadian Journal of Physiology and Pharmacology, 90(6), 697–703.
Astor Scientific Team. (2026, April 24). Plasticware vs. glassware: Which is better for your lab needs? Astor Scientific.

The Scientist. (n.d.). Preventing leachable plastic from disrupting bioassays.
Xu, Z., Gartia, M. R., Choi, C. J., Jiang, J., Chen, Y., Cunningham, B. T., & Liu, G. L. (2011). Quick detection of contaminants leaching from polypropylene centrifuge tubes with surface‐enhanced Raman spectroscopy and ultraviolet absorption spectroscopy. Journal of Raman Spectroscopy, 42, 1939–1944.
Re-use of laboratory utensils reduces CO2 equivalent footprint. (n.d.).
Re-use of labware reduces CO2 equivalent footprint and running costs in laboratories. (n.d.). bioRxiv.
Schmizo AG. (n.d.). Schlenk flask.
Wikipedia contributors. (2025, November 9). Schlenk flask. In Wikipedia, The Free Encyclopedia.

DWK Life Sciences. (n.d.). Soda lime vs borosilicate glass in the laboratory.
Thomas Scientific. (n.d.). Soda lime vs. borosilicate glass in the laboratory: What scientists need to know.
Quest Diagnostics. (n.d.). Specimen collection tubes.
Yelimeshyn, S. (2025, December 24). Test tubes in the laboratory: Types, functions, and what to know before you buy scientific tubes. BostonMed Supply.

Tiwari, G. (2024, August 17). Test tubes: Types, uses, and laboratory applications. Medikabazaar.
Wikipedia contributors. (2025, December 6). Test tube. In Wikipedia, The Free Encyclopedia.
Lab Manager. (n.d.). The ultimate guide to test tubes: Uses, types, and buying considerations.

East Side Clinical Laboratory. (n.d.). Tube types.
University of Minnesota. (n.d.). University health and safety guidance document: SCHLENK LINE.
Becton, Dickinson and Company. (2021). Vacutainer® evacuated blood collection system.
University of Wisconsin-Madison. (n.d.). Vacuum system (VS) and Schlenk line (SL) safety.

Stone, D. (2023, June 22). What are the different tube types used in a lab? Pipette.com.
Asynt. (n.d.). What is a Schlenk line – plus the Schlenk line survival guide.
Westlab. (2017, July 31). What is the difference between soda-lime glass & borosilicate glass?

Laboratory Test Tube – Types, Limitations, Advantages, Uses