Test Tubes Definition & Uses

Test tubes are an integral part of any laboratory whether it is for chemistry, biology, medical, or other purposes. However, test tube lab equipment comes in a wide variety of purposes, hence varying in shape, color, and design.

So whether you want to set up a lab or upgrade the applications, knowing the basic information about each test tube is essential. Hence we’ve prepared this comprehensive guide covering basic information on all types of test tubes used in laboratory settings to help you collect the right items for certain applications.

What Are Test Tubes?

In short, a test tube is simply a plastic or glass tube with one end closed off. Though most test tube lab environments feature glass materials, some labs, like pathological laboratories, use clear and sterile plastic test tubes.

The most common usage of test tubes is holding powdered material or liquid and keeping them vertically. Test tubes need to be stored in a test tube rack that helps them remain upright and prevent accidental jolting.

How Test Tubes Are Used

Glass test tubes are usually used to heat substances inside them. The test tubes are quite thin and considerably strong, making them an ideal container for heating liquids. Therefore, most glass test tubes are designed with rounded bottoms and are mostly used in a test tube chemistry lab.

Depending on the usage, test tubes are also known as sample tubes or culture tubes. In bioscience or microbiology labs, plastic test tubes are used to hold any kind of small living organisms like fungi, bacteria, or plant seedlings.

Compared to typical test tubes that remain vertically, culture test tubes remain horizontally during breeding microorganisms to maximize the surface area. In medicine and pathology laboratories, sterile plastic tubes are used to collect and hold body fluids like test tubes of blood such as urine and blood.

Types of Test Tubes Based on Size

Ignition Tubes

Ignition tubes are handy lab equipment to heat small quantities of solid powder material directly for longer times at higher temperatures. The reason is that a typical glass tube can’t cut it here as it may melt down over time.

Hence ignition tubes are designed especially for this purpose and made of thick, toughened borosilicate glass. Sodium fusion is another challenging reaction where ignition tubes are helpful. However, the downside is that you can’t use a normal test tube holder clamp to clean these tubes effectively.

The reason is that ignition tubes cause melted residues at the bottom side, which are very difficult to scrape using a normal test tube holder function. Additionally, ignition tubes are quite small and brittle; hence need to be handled in a disposable manner.

Boiling Tubes

Though a glass test tube is great for heating liquids, it causes problems during attempting to boil the liquid. During boiling liquids in such small enclosures, the test tube doesn’t get a sufficient area to allow the gas out.

So during boiling aggressively, the liquid may blow up out of the tube and may end up causing awful accidents as well as damaging burns.

Hence, a bigger-sized test tube is used in the test tube stand in the chemistry lab, particularly for boiling things for some time. These test tubes are made of thicker walls and stronger construction.

Types of Test Tubes Based on Material

Borosilicate Glass Test Tube

Borosilicate glass is manufactured from 70% to 80% silica, 7% to 13% boric oxide, and a small amount of aluminum oxide and alkaline sodium oxide. Borosilicate glass is superior to soda-lime glass in various ways. It is less susceptible to chemical assault and has a lower expansion coefficient, making it more resistant to thermal stress.

Soda Lime Glass Test Tube

This is one of the most common test tubes found in glass and is used for a variety of purposes. Soda-lime glass is also considerably inexpensive, tough, and chemically stable.

Quartz Glass Test Tube

Quartz glass is made of a combination of high infrared (IR) radiation transmission rate and tough thermal shock resistance. This laboratory equipment test tube is also chemically robust and chemically pure and comes with decent high-temperature qualities.

Types of Test Tubes Based on Uses

Reusable Test Tubes

Borosilicate Glass 3.3 produces reusable test tubes, which can be reused following sterilization. This sort of test tube also comes in culture tube and glass tube variations where the culture tubes are usually used to house cell cultures. Reusable tubes are also recyclable.

Disposable Test Tube

The disposable test tube is usually made of two types of glass, including boro 7.0 and boro 5.1. Boro 5.1 produces two different varieties, including culture tubes and glass tubes. Apart from that, disposable tubes are a cost-efficient option and can be discarded after use.

Types of Test Tubes Based on Color

Test tube diagram collections often use color-coded tubes for easy identification.

• Yellow, Pink, and Blue: These shades represent culture bottles needed for blood culture.

• Light Blue: Citrate tubes are used to draw blood for coagulation investigations.

• Red: These tubes don’t have additives and are used to activate the coagulation cascade.

• Green: Heparin is used in these tubes to block the thrombin product.

• Lavender: Contains EDTA and is used for hematologic analyses.

• Grey: Contains potassium oxalate and sodium fluoride for measuring lactic acid and plasma glucose.

In clinical practice, additional colors such as tiger, gold, and pink have their unique applications.

Conclusion

Test tubes are extremely versatile and helpful laboratory equipment to mix, heat, or store chemicals for laboratory and assay research. The tube holder function is crucial in keeping them stable during experiments. The test tube science world requires careful selection based on use, material, and even color coding. As you can see, test tubes come in a wide variety of types, shapes, and colors that are designed for unique purposes. Hope this guide helps you collect the right test tube for your lab for certain research and analysis.

FAQs

What are test tubes used for in laboratories?

Test tubes are used to hold, mix, or heat substances in laboratory settings. They are commonly used in chemistry, biology, and medical labs for experiments, storing chemicals, and collecting biological samples.

What are the different types of test tubes based on material?

The main types of test tubes based on material include borosilicate glass (resistant to thermal stress), soda-lime glass (common and inexpensive), and quartz glass (resistant to high temperatures and chemical damage).

What do the different colors of test tubes indicate?

Test tubes are color-coded for easy identification. For example, yellow, pink, and blue are used for blood cultures, light blue for coagulation tests, red for coagulation without additives, and lavender for hematologic analyses. Each color serves a unique purpose in clinical and laboratory practice.