Affiliation

• ¹Department of Science and Engineering, Chuo University, Kasuga Bunkyo Tokyo, Japan
• ²NGK Insulators, Suda Mizuho Nagoya, Japan
• ³Medical Department, Uehara Nishihara Nakagamigun Okinawa, Japan
• ⁴Applied Electrostatistics Laboratory, Toyohashi University of Technology, Hibarigaoka, Tempaku, Toyohashi, Aichi, Japan
• ⁵Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta Midoriku Yokohama, Japan

Corresponding Author

Hideharu Shintani, Department of Science and Engineering, Chuo University, Kasuga Bunkyo 112-0003, Tokyo, Japan, Tel: +81338171733; E-mail: shintani@mail.hinocatv.ne.jp ; hshintani@jcom.zaq.ne.jp

Citation

Shintani, H., et al. Efficiency of Atmospheric Pressure Nitrogen Gas Remote Plasma Sterilization and the Clarification of Sterilization Major Factors. (2015) J Pharm Pharmaceutics 2(1): 22- 28.

Copy rights

© 2015 Shintani, H. This is an Open access article distributed under the terms of Creative Commons Attribution 4.0 International License.

Keywords

Abstract

  Experiments reported here were conducted using atmospheric nitrogen gas remote plasma with a pulsed power source. The sterilization efficiency, major sterilization factors and most appropriate sterilization conditions were determined. By varying several factors such as hotplate temperature; relative humidity, water vapor supply location, etc., the most appropriate sterilization conditions were identified. The temperature of the hotplate was varied from 55°C to 75°C and with this 20°C increase in temperature, sterilization was completed in half the time. In this experiment, it was confirmed that the combined effect of a relative humidity (RH) of 0.5% and nitrogen gas was superior to the use of nitrogen gas alone. Furthermore, it was clarified that the optimal humidity was in the range of 0-5 % RH. When RHs of 0, 0.5 and 5% were tested, 0.5% RH was found to be optimal for sterilization. The location of the water vapor supply was changed relative to the hotplate, and use of the most remote port upstream of the reactor resulted in the most efficient sterilization. In addition, the results correlated with the amount of NO radicals generated. The NO radical is the precursor of OONO•- (peroxynitrite anion radical). The sterilization factors associated with this experiment were NO radicals, H₂O₂, OH radicals, O₂•- (superoxide anion radicals) and OONO•- only OONO•- production correlated with sterilization efficiency. Therefore, OONO•- is thought to be the major factor for nitrogen gas plasma sterilization. In addition, as already described, the highest sterilization efficiency was with 0.5% RH and the amount of OONO•- produced correlated with the RH. These data support the idea that OONO•- is the major contributing factor for nitrogen gas plasma sterilization. The D values for this experiment were approximately 10 min.