CENTRIFUGES

Variable features of centrifuge

• Maximum speed • Vacuum • Temperature control• Volume of samples

Small bench top centrifuges

• Maximum speed 4000 to 6000 rpm• RCF is 3000 g force • Can operate at ambient temperature • Rotors used

Low speed centrifugation

• Refrigerated centrifuge • Maximum speed of 6000 rev.per minute• RCF is 6500g force• Large carrying capacity • Interchangeable rotors • Accurate balance needs to be done • For RBCs, nuclei and chloroplasts

High speed centrifuge

• Very high speed• They can go upto 25,000 rev perminute • RCF is 60,000 g force• Interchangeable rotors • Used for pelleting micro organisms, cellular

debris and so on

Ultracentrifuges

• Very high speed of 70,000 rpm and more • Rotors are run in high vacuum • Lot of sophistication is required• Rotors do not have to be aerodynamically

designed • RCF of 500,000 g force • Can be used for membrane fractionation and

viruses and so on

Ultracentrifuges can be of 2 types

• Preparative ultracentrifuge• Analytical ultracentrifuge

Preparative ultracentrifugation

• Maximum speed of 80,000 rpm • RCF is 600,000 g force• Sealed evacuated rotor chamber• Temperature monitoring system• Electronic circuits that detect rotor imbalance• Flexible drive shaft • Protected in armor shield • Table top centrifuges present • Used for sub cellular organelles, viruses etc.

Analytical ultracentrifuge

• They have a system for detection• i.e. they have optical systems • They have 3 types of optical systems a) Absorbance optical system b) Alternative schlieron system c) Rayleigh optical system

Rotors

Types of rotors: a) Fixed angle rotors

• Swing out bucket rotor

• Vertical rotors

References

• Principles and Techniques of Biochemistry and Molecular Biology by wilson and walker

• http://www.thermoscientific.com• http://www.phys.sinica.edu

THANK YOU…