![]() The data indicate that the survival curves for liquid chemical sterilants may not exhibit log-linear kinetics and the shape of the survivor curve may vary depending of the formulation, chemical nature and stability of the liquid chemical sterilant. The information that is available in the literature suggests that sterilization processes based on liquid chemical sterilants, in general, may not convey the same sterility assurance level as sterilization achieved using thermal or physical methods 823. The survival kinetics for thermal sterilization methods, such as steam and dry heat, have been studied and characterized extensively, whereas the kinetics for sterilization with liquid sterilants are less well understood 921. Generally, chemical liquid sterilants cannot be monitored using a biological indicator to verify sterility 899, 900. These solutions are commonly used as high-level disinfectants when a shorter processing time is required. However, except for a few of the products, the contact time is based only on the conditions to pass the AOAC Sporicidal Test as a sterilant and not on simulated use testing with devices. The indicated contact times range from 3 hours to 12 hours. ![]() Several FDA-cleared liquid chemical sterilants include indications for sterilization of medical devices (Tables 4 and 5) 69. ![]() The primary lethal process is considered to be oxidation of cell constituents. atrophaeus spores should be used to monitor the sterilization process for dry heat because they are more resistant to dry heat than are G. The most common time-temperature relationships for sterilization with hot air sterilizers are 170☌ (340☏) for 60 minutes, 160☌ (320☏) for 120 minutes, and 150☌ (300☏) for 150 minutes. ![]() In addition, the high temperatures are not suitable for most materials 919. The disadvantages for dry heat are the slow rate of heat penetration and microbial killing makes this a time-consuming method. The advantages for dry heat include the following: it is nontoxic and does not harm the environment a dry heat cabinet is easy to install and has relatively low operating costs it penetrates materials and it is noncorrosive for metal and sharp instruments. This method should be used only for materials that might be damaged by moist heat or that are impenetrable to moist heat (e.g., powders, petroleum products, sharp instruments).
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