How to Choose the Right Microcentrifuge Tube for Your Needs
Compare volume, centrifugation limits, colors, package quantities, and special features using the selection chart. Expand the topics below for more information about RCF, clarifiers, sealing, and other features.
Download the selection chart for microcentrifuge tubes.
Microcentrifuge tubes can be specialized for specific tasks or designed for general purpose use. Consider whether you need a tube for just one task or if you would like a tube that will work throughout your entire experiment. Some of the common requirements for tubes are listed below.
Click on a link below to expand it for more information.
Centrifugation (RCF, temperature, and length of run. Click to expand.)
Microcentrifuge tubes are rated for maximum relative centrifugal forces (RCF). If you are spinning at or near the maximum, note the temperature and length of time of your experiments. Higher temperatures and longer run times create additional stresses during centrifugation. Also, as laboratory centrifuges become more powerful, watch that your tube’s limits are keeping up with the forces of your new equipment. Excessive stress can cause deformation, cracking, or breakage if your tube is not strong enough.
If you need to resuspend a large pellet or have a very small pellet that is difficult to view in a 1.5 ml tube, consider the Seal-Rite 2.0 ml tube. The broad, rounded base creates an off-center, less compact pellet that is easier to resuspend.
Clarity (The effects of clarifying additives. Click to expand.)
Pure polypropylene exhibits a slight opacity that varies with the thickness of the tube. Very clear tubes often contain clarifiers. These additives can leach into the contents of the tubes, especially when the tubes are subjected to higher temperatures, solvents, or lengthy experiments. When choosing a tube with clarifiers, consider the sensitivity of your experiments. Could the leaching of additives affect your results? Clarifiers can also weaken tubes and cause a decrease in RCF limits, especially after autoclaving.
Closing and Sealing (Opening and closing forces; seal construction. Click to expand.)
If you are using a lot of tubes, you’ll want a tube that is not difficult to open or close. Opening and closing forces vary among tube brands and can be influenced by materials, cap design, production tolerances, and temperature. Broad, beveled cap rims help distribute opening forces for more comfortable handling.
A complete seal is critical if you are performing reactions, storing samples, or just trying to avoid evaporation. There is no standardized rating system for tube sealing, so how do you know which tube meets your needs? Before you judge the sealing performance on a sound or the visual appearance alone, consider the design of the tube. The cap plug and the interior of the tube must be created as a system. The entire outer ring of the cap plug and the inner ring of the tube must make contact without any gaps where leakage or evaporation could occur. When both surfaces are properly engineered and constructed, the cap slides into the sealing area with a defined resistance. No snapping sound is created. In fact, snapping during closing may indicate a deformity of one of the surfaces, leading to a rush of air through a gap between the cap plug and the interior of the tube. Thin, short cap plugs will deform more easily and provide less opportunity for complete surface contact.
A few simple experiments in your lab can test the seal of a tube. Add a liquid with a low surface energy to the tube and lay it on its side for a period of time to check for leaks. Or, pipet a defined volume of liquid into the tube, place it in a dry bath at 95°C, and examine the contents for evaporation. When boiling a tube, remember that absence of tube popping may indicate one of two situations – you either have a tube with a great seal or one with a small leak that vents out the pressure.
Labeling (Click to expand.)
Pure polypropylene tubes accept labels and marking pens more readily than tubes made with clarifiers, copolymers, or low adhesion formulations.
Packaging (Click to expand.)
Tubes should be securely packaged in plastic to protect their cleanliness. Tamper evident strips will let you know if anyone else in the lab may have opened the bag, and resealable zip tops help you avoid spills or contamination after the bag is opened. RNase, DNase, and DNA free certification is recommended for molecular biology applications. Sterilized tubes provide additional convenience and pyrogen-free testing.
|Can your tube pass all of these tests? Seal-Rite® can.
|Centrifugation at 25,000 x g for extended periods
|No clarifiers to affect results
|Maintains a seal while boiling