Run Times; Run Speeds - Beckman Coulter JA-25.50 Manual

JA-25.50 Rotor

RUN TIMES

RUN SPEEDS

SPEED
2
Based on sedimentation in water at 20°C. Assumes full tubes.
14
Polycarbonate and Polyallomer Bottles
Capped polycarbonate and polyallomer bottles may be centrifuged
completely filled, or partially filled (not less than half full).
Containers placed in opposing positions in the rotor must be filled
to the same level.
To pellet particles of known sedimentation coefficient s, calculate the
run time t using the k factor (395) of the rotor.
is in Svedberg units.
For example, at 25 000 rpm, mammalian viruses (s = 700 S) can be
pelleted in
The centrifugal force at a given radius in a rotor is a function of run
speed. Comparisons of forces between different rotors are made by
RPM/RCF
comparing the rotors' relative centrifugal fields (RCF). When rota-
tional speed is selected so that identical samples are subjected to the
same RCF in two different rotors, the samples are subjected to the
same force (see Table 4).
⎛
k 25 000
- - -------------------------------------- -
=
t
⎝
s actual run speed
2
⎛ ⎞
395 25 000
≈
-------- - --------------- -
=
t 30 minutes.
⎝ ⎠
700 25 000
2
Time is in hours and s
2
⎞
⎠
(1)
(2)