Laboratory test tubes come in many different sizes, materials, and styles suited for different experiments and conditions. Having so many options can be overwhelming, so we created a guide explaining tube choices. It’s best to review the strengths and limitations of every tube type. See below to find the best test tube for your laboratory needs. 

What size test tube do I need?

Test tubes are available in a wide variety of sizes, with the most standard ranging from 0.5mL microtubes to 50mL centrifuge tubes. When choosing test tube sizes, consider the volume sizes of your samples. When working with small sample sizes, microtubes are a great option. If you will be working with larger volumes or centrifugation, you will need a 15mL or 50mL conical tube. Consider scalability if you need to account for potential volume increases due to varied experiments or expansion from reactions. You should also evaluate labeling needs, storage space, and compatibility with laboratory automation equipment. Scinomix tube handling equipment can accommodate tubes from 0.5mL to 50mL, but other systems may require specific labware.   

What test tube material is best for my laboratory research?

Glass, Plastic, or Polypropylene Test Tubes

Glass has a high resistance to heat and chemicals. Glass test tubes are suitable for experiments using very high temperatures, direct flame, or corrosive substances. However, this material is prone to breaking if mishandled, posing risks of sample loss and safety issues. Due to its heavier weight and fragility, glass is often not compatible for laboratory automation systems or high-throughput systems.

Laboratories may opt for plastic test tubes due to their durable, shatter-proof material. Plastic tubes are generally less expensive than glass, especially when purchased in bulk, making them ideal for routine lab use. Some plastic materials have thermal limitations and may react with certain chemicals, potentially causing contamination; however, many plastic tubes are now made with specialty materials like polypropylene for higher resistance. 

Polypropylene test tubes are commonly used for biological samples due to their durability. This material is suitable for a wide range of applications, withstanding a temperature range of -196℃ to 121℃. Polypropylene tubes can be autoclaved for sterilization making them ideal for microbiological and cell culture work. These tubes are also resistant to many chemicals including acids, alkalis, and organic solvents. Polypropylene can withstand mechanical stress better than glass. Polypropylene test tubes’ durability proves them optimal for automation and high-throughput environments. 

Which test tube base type should I choose?

Skirted or Conical Test Tubes

Conical test tubes are designed for centrifugation, the separation of particles from a solution. The shape allows for the formation of a tight pellet at the bottom. These tubes are suited for cell pelleting, protein precipitation, and nucleic acid extraction. Conical tubes are automation-friendly, but skirted bases are often recommended for laboratory automation.

Skirted test tubes are ideal for use with automated laboratory equipment like automated tube labelers and automated aliquoting systems. Their flat bases offer better stability, even weight distribution, and consistent orientation with less reliance on racks. Precise alignment ensures accuracy. 

What test tube color is best for my experiments?

Amber or Clear Test Tubes

When choosing the color of your test tubes, consider the specific needs of your experiments regarding light sensitivity, chemical compatibility, and visibility. Clear tubes are suitable for a wide range of laboratory applications including sample storage, biological assays, and chemical reactions. Easy visual inspection allows laboratory personnel to better monitor reactions and volumes. Researchers can easily track samples without additional labeling and handling using clear tubes. Depending on the materials used in your research, it is important to know that clear test tubes do not protect light-sensitive samples. 

Amber test tubes protect against UV and visible light. They are ideal for storing and handling pharmaceuticals, vitamins, and other light-sensitive compounds. Protecting these types of materials from light exposure maintains sample stability, preventing inaccurate results.

Should I use test tubes with ribbing?

Ribbed or Non-Ribbed Test Tubes

Both ribbed and non-ribbed test tubes are suitable for many laboratory applications from sample storage to complex chemical reactions. The textured surface of ribbing improves grip. Enhanced control of ribbed test tubes can benefit laboratory personnel handling tubes with gloves or in wet conditions. Test tubes with and without ribbing are compatible with laboratory automation, but ribbed tubes can offer easier handling by robotic systems due to the enhanced grip. 

Should I use a graduated test tube?

Graduated test tubes are great for quantitative analysis when reagent and sample volumes must be precise. Etched or printed volume markings on graduated test tubes help laboratory personnel add or remove exact measurements of liquids across multiple experiments. Automated liquid dispensers and automated aliquoting systems are effective tools for researchers who need to precisely fill large numbers of samples. Test tubes with and without graduation marks are both compatible with laboratory automation systems. 

What is the difference between internally- and externally-threaded caps?

Cryo test tubes are often available with internally-threaded or externally-threaded caps. Both tube options are automation-friendly and suitable for biobanking and other high-throughput applications. Tubes with internal threads seal from the inside for a more streamlined footprint that can be better for storage purposes. External threads are located on the outside of the tube, which can reduce contamination risk by eliminating the possibility of sample materials coming into contact with the threads. External threads also reduce the potential of spilling sample materials when uncapping. 

Do I need sterilized test tubes?

Unsterilized and Sterilized Test Tubes

Choosing between sterilized and unsterilized test tubes depends on the requirements of your experiments. Sterilized test tubes are free from microorganisms and contaminants to better maintain the integrity of your samples. Researchers working in cell culture, microbiology, and molecular biology may opt to purchase pre-sterilized tubes to avoid the time and effort of in-house sterilization. Unsterilized test tubes may be purchased for simple mixing, storage of non-sensitive samples, or other routine laboratory tasks in which sterility is not critical. 

Test tubes can make or break a scientific study. It’s critical to consider what type of materials and experiments you will be working with throughout your research. Ask if the tube is compatible with the required volumes, reactions, protection, and equipment. You may need to create a checklist based on the information provided above to ensure that your tube choice works with every aspect of your research. 

At Scinomix, we strive to simplify lab processes while ensuring top-quality results. In addition to our innovative automation solutions, we provide quality consumables validated for laboratory automation including test tubes, labels, and racks. Our commitment to optimizing your laboratory efficiency led us to create a tube product line that is manufactured in the US and readily available. Our short lead times and competitive pricing allow you to streamline your supply chain.

Learn more about Scinomix laboratory test tube product line.