Ultracentrifugation Catalog

www.centrifugebybeckman.com

Reference

Useful Formulas

k Factor

To determine k Factor

ln ( r

/ r

)

2.53 × 10 5 ln ( r

/ r

)

10 -13 3600

max

min

max

min

k =

OR k =

×

(rpm/1000) 2

ω 2

To determine pelleting time ( t)

t = where s = sedimentation coefficient in Svedbergs k s

To relate pelleting time between rotors

k

= k 1 t 1

2 t 2

To adjust k Factor for runs less than maximum rotor speed

(

) 2

adj = k maximum rated speed of rotor actual run speed

k

To relate relative centrifugal force (RCF) to speed (rpm):

( ) 2 rpm 1000

RCF

= 1.12 r

OR rpm = 10 3

RCF

1.12 r

max

max

max

To relate the sedimentation coefficient ( s ) to rotational speed:

4

1 ω 2 r

dr dt

s =

×

Svedberg unit (S) equivalent:

S = 10 -13 seconds

Reduced run speed for dense solutions:

reduced run speed = max rated speed of rotor × A/B

where A = max. permissible density of rotor tube contents, and B = actual density of the tubes to be centrifuged

4-12

Beckman Coulter Ultracentrifuge