What to Look for in a Centrifuge

A centrifuge is a central piece of equipment in many laboratory protocols, but with a vast number of centrifuges on the market, choosing the right one for your specific experimental needs is crucial.

Getting the best model for both your lab and your samples relies on truly understanding your demands —so ask yourself some basic key questions. How fast does your centrifuge need to go? How many samples are you looking to spin? Will you be using tubes, and of what size and shape? Or will you be using microplates? Or bottles? Is refrigeration needed? Will biocontainment be required? Answering these questions will help guide you through the selection process.

Speed

How fast your centrifuge needs to spin is central to your selection. But while people traditionally think about the revolutions per minute (RPM), “the relative centrifugal force (RCF) or G-force is what you should consider,” says Peter Will, Market Product Manager, OHAUS Corporation. “RCF indicates the true force the samples inside the rotor are exposed to,” explains Will. Typically, molecular biology and biological sample separations of cellular materials, RNA/DNA, and peptides are high-spin applications, requiring higher RCF. Cell culture and clinical applications such as blood separations, by contrast, can be performed at lower RCF. Although for clinical applications, choosing a model with fast acceleration and deceleration rates to process urgent requests may be advantageous.

Vessel format and size

Knowing the vessel type and size you will be spinning is also key. The model you pick needs to have rotor options that are compatible with your vessel of choice. Will you be using tubes? And if so what shape and size? Or are you working with plates/bottles/bags? For molecular biology applications, pick rotors with extended necks that allow them to accommodate DNA preparation kits. Flexibility is also important to consider. For cell culture applications, choose a model able to accept both microplates and conical tubes for maximum workability.

The “vessel type and size will also determine the capacity of how many tubes or bags each centrifuge can hold,” explains Atalay Tok, Application Scientist at Thermo Fisher Scientific. In the case of bioproduction and bioprocessing, a centrifuge that holds the highest vessel volume is important, but this means less tubes can be spun at once. In clinical applications, sample volumes are smaller but tend to be processed in larger amounts—so a centrifuge that can hold a large number of tubes is essential.

Sample volume can also influence the centrifuge configuration you require. While both high and low spin centrifuges are available as bench top and floor standing models, if you require larger sample volumes such as liter bottles or blood bags—a floor standing centrifuge is required.

Temperature range

Temperature is another important consideration. Is the temperature of your samples critical? Broadly speaking, there are two types of centrifuges—ventilated and refrigerated. Ventilated models spin at a temperature slightly higher than the ambient, with this temperature increasing during the cycle. For this reason, they are appropriate “for applications where precise temperature control is not critical,” explains Tok. Refrigerated models by contrast, contain cooling systems, that allow precise temperature control and a lower internal temperature during operation. This is vital in applications such as molecular biology, where a lower temperature is needed to reduce sample degradation, and in clinical and cell culture laboratories, where precise temperature reproducibility is essential to eliminate variation in processing.

Control and management

Choosing a centrifuge that provides simple, intuitive control is also an advantage. Models now offer easy-to-use touch screen interfaces that provide advanced programming options; allowing “multiple users to pre-program different settings is essential in a multi-user environment,” explains Will. Other models offer password protection and allow users to monitor usage.

Furthermore, “integration with other laboratory equipment and the ability for remote control are becoming more critical,” says Will. And as Tok, explains, this is increasingly important in regulated environments such as gene therapy and blood banking. The connectivity “supports clear audit trails and GMP/GLP compliance,” giving lab managers the assurance they need.

Other considerations

Flexibility

While you need a centrifuge to meet your current needs, you should also choose a model that can accommodate “if and when your research goes in a different direction,” states Will. “Hybrid centrifuges suitable for both high-speed and low-speed applications are critical in settings with multiple users.” Also look for models with rotors that can be easily changed, allowing the freedom of being able to fit multiple vessel sizes and formats. After all, as Will reminds us ,“it is cheaper to buy a new rotor than a new centrifuge.”

Biocontainment

In the case of some clinical and gene therapy applications, “a centrifuge with certified biocontainment features needs to be considered to protect samples against contamination, and users from highly contagious clinical samples,” Tok explains. Choose models with sealed rotors and certified biocontainment lids to reduce risk of spread bio-hazardous substances.

Safety and ease of use

Be on the lookout for centrifuges with built in safety and user comfort features. Electronic lid-locks, automatic rotor recognition, and rotor imbalance detection all provide greater user protection —particularly in high spin models. Features such as self-balancing rotors, low-noise or soundproof boxes, and easy rotor exchange systems also improve the user experience and convenience.

Conclusion

Choosing the right centrifuge for your research is an important decision. While speed, vessel capability, and refrigeration are central to this choice, factors such as flexibility, ease of use, and service warranty should also be considered. More recently, technological innovations that allow greater connectivity and monitoring are becoming increasingly important, and can give users the assurance of safety and compliance they need.