Ultraviolet Sterilizer for Celluloid Tubes

In the course of describing a high speed, air-driven centrifuge for the study of viruses, Bauer and Pickels 1 reported the use of celluloid tubes as satisfactory containers capable of withstanding high centrifugal forces. The tubes are transparent, light, flexible, and practically nonbreakable. More recently Horsfall 2 pointed out their advantage over glass containers for the storage of certain labile biological material at the temperature of solid CO2. They now also are used frequently for shipping labile material packed in dry ice. The extensive use of celluloid tubes has been handicapped by the difficulty of sterilizing them. Any form of heating deforms them or renders them brittle, and chemical agents such as alcohol are also unsatisfactory. Thus there has existed an urgent need of a practical method of dry sterilization, and the purpose of this paper is to describe a simple apparatus for the sterilization of celluloid tubes by means of ultraviolet light. The sterilizer consists essentially of a cabinet and 3 enclosed ultraviolet lamps, which, with the aid of a suitable reflector, direct their illumination downward into the openings of the tubes. As celluloid absorbs ultraviolet light, the certainty in sterilization of a tube depends on every element of its internal surface being supplied with an uninterrupted beam of the radiation, either directly from a lamp or by reflection from a good mirror surface. The present apparatus is designed to accomplish this with tubes∗ which are 1/2 inch in diameter and 3 1/2 inches in length, and which are provided at the top with impressed threads for metal screw caps. Although such tubes were used in testing the efficacy of the sterilizer, it was found to function equally well, as might be expected, with tubes of other dimensions, provided, however, that the ratio of length to diameter was not greater than 7.