11.2.2 PC centrifuge tube cleaning
PC material has relatively low chemical stability to alkaline solvent, therefore use of cleaning agent with
pH value of over 9 should be avoided. Some neutral cleaning agents still have pH value of over 9 after
being diluted as recommended by the vendor, therefore use of cleaning agent with pH value of 7-9 is
recommended.
11.2.3 Autoclaving of PA, PC and PP centrifuge tube
PA begins softening at the temperature of 120
℃
, while PC and PP begin softening at 130
℃
. Generally,
PA may be sterilized for 30 minutes at 115
℃
(0.7 kg/cm2), while PC and PP may be sterilized for 20
minutes at 121
℃
(1.0 kg/cm2). Too high temperature would result in deformation of centrifuge tube.
Take the following steps, if using an autoclave:
(1) Place the centrifuge tube upright with opening facing upward. If the centrifuge tube is placed in an
inclined or horizontal manner, it will deform due to the effect of gravity.
(2) Remove the threaded cover and inner cover to prevent deformation or crack of the centrifuge tube.
(3) Take the centrifuge tube only when the autoclave cools down to room temperature.
11.2.4 Service life of centrifuge tube
The service life of plastic centrifuge tube depends upon the nature of sample, rotor speed and
centrifugation temperature. When the plastic centrifuge tube is used for centrifugation of conventional
neutral samples (pH5-pH9), its estimated service life at the maximum rotation speed is as follows:
High-quality centrifuge tube (PA, PC, PP): 30-50 times.
Conventional centrifuge tube: about 10 times (number of uses may be increased in case of low-speed use)
Notes: (1) The service life of centrifuge tube is also related to the cleaning and sterilization conditions;
(2) Never use any centrifuge tube with cracks on it.
12. RCF calculation
Relative centrifugal force (RCF
）
can be calculated using the following formula:
RCF=1.118×r×n
2
×10
-5
r-rotation radius, unit: cm; n-rotation speed, unit: rpm
