32
Gas sterilization
Ethylene oxide
O
X
O
Formaldehyde
O
O
O
PA: Polyallomer; PC: Polycarbonate; PP: Polypropylene
2) Cleaning PC tubes and bottles
PC materials have low chemical stability against alkaline solutions, so avoid using
detergents with pH higher than 9.
Note that some neutral detergents
’ pH is still higher than
9 even if diluted according to the instruction. Use detergent with its pH between 7.0 and
9.0.
3) Sterilize PA, PC and PP tubes and bottles by autoclave
PA begins softening at about 120
℃
, and PC and PP at about 130
℃
. So disinfect PA
tubes/bottles at 115
℃
(0.7kg/cm
2
) for 30 minutes and PC and PP tubes/bottles at 121
℃
(0.1kg/cm
2
) for 20 minutes when using the autoclaving. If the temperature is exceeded,
the tubes/bottles may deform.
Please take the following instructions when using a sterilizing vessel:
(1) Place bottles in vertical position with mouths upward. If bottles are inclined, they may
deform due to gravity action.
(2) Remove caps and inner covers to avoid deformation or rupture.
(3) Take the bottles out till the sterilizing chamber cools down to the room temperature.
4) The lifetime of tubes and bottles
The lifetime of plastic tubes and bottles depends on the characteristics of samples,
speed of the rotor, temperature and so on.
When the plastic tubes/bottles are used for ordinary centrifugation (pH between 5.0 and
9.0), their life expectancies are defined as follows:
When operated at the maximum speed:
High quality tubes and bottles (PA, PC, PP): 30-50 times
Ordinary tubes and bottles (PA, PC, PP): about 10 times
The lifetime of the plastic tubes/bottles also depend on the treatment conditions such as
cleaning and sterilization.
