The spectrophotometer (The centrifuge)

Dr Smith: ‘Alright everyone, now that we’ve covered our weighing techniques, let’s move on to another piece of essential equipment in our biology lab: the centrifuge.’ She points to the microcentrifuge in the corner. 

Figure: Microcentrifuge (Ajay Kumar Chaurasiya, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons) 

Some basic information on the Centrifuge:

1. The centrifuge works by spinning samples at high speeds. Heavier particles move outward to the bottom of the tube, and lighter ones remain near the top.

2. You’ll see the term ‘g-force’ or ‘relative centrifugal force’ (RCF) listed, which describes the strength of the force acting on your sample.

3. Different protocols require specific speeds and times, so always consult your lab manual or the relevant literature.

Dr Smith: ‘Now, in our setting, we typically use this small, benchtop centrifuge. It has a digital display where you can set the speed in revolutions per minute (RPM) or in RCF, depending on which is specified in your protocol. The rotor inside holds tubes at an angle or vertically, depending on the model, and you must always balance your tubes in pairs or use a balance tube of equal weight’.

She continues to present four common experiments in Biology labs. Decide whether you would need to use a centrifuge or not keeping in mind that there might be more than one correct answer: