To avoid bacterial contamination of germfree animals, it is indispensable that invisible breakages of drum type vinyl sleeves, often causes of contamination, should surely be detected by usual tests as well as aseptic experimental procedures. The tests used generally, however, are not reliable although they need a considerable amount of time. A new method was attempted to detect the breakages of the sleeves by means of measuring the electric resistance between the inside and the outside of the vinyl sleeves (CLEA Japan inc.).
The results obtained were as follows.
(1) Infinite values of electric resistance were observed in all dry vinyl sleeves when they were unbroken, whereas the electric resistance values were decreased and the minimum value of 120KΩ was observed at the opening for disinfectant spray in the moist vinyl sleeves.
(2) The electric resistance values of broken sleeves were ranged from 1.7KΩ to 29KΩ and the remarkable differences were recognized between the electric resistance values in the unbroken and the broken sleeves.
It is assured, therefore, that the breakages of the vinyl sleeves, even invisible, are able to detect easily and reliably by means of measuring the electric resistance.