Centrifuge Best Practices

Converting RPM (revolutions per minute) to RCF (relative centrifugal force) is a common task in laboratory settings when using centrifuges. It involves a straightforward calculation using the rotor radius, while the k-factor provides a means to evaluate and compare the efficiency of different centrifuge rotors. Understanding both concepts is crucial for optimizing centrifugation protocols in the laboratory.

Relative Centrifugal Force (RCF) is a measure of the force exerted on a sample in a centrifuge, relative to the force of gravity. The formula to convert RPM to RCF is:

g = (1.118 x 10-5) x r x RPM²

• g is the relative centrifugal force (RCF).
• r is the radius of the rotor in centimeters (cm).
• RPM is the speed of the centrifuge in revolutions per minute.

The k-factor is a value that describes the efficiency of a centrifuge rotor in pelleting particles. It is used to compare the relative performance of different rotors and is particularly useful when switching between rotors or centrifuges.

The k-factor is particularly important for:

• Comparing the performance of different rotors.
• Estimating the time required for pelleting particles of a given size and density.
• Standardizing protocols across different centrifuges and rotors.