The factors that affect the sterilization effect are temperature, humidity, concentration, time, pressure, packaging method, etc.
The conventional limit of temperature is generally 44 ℃ ~ 56 ℃, and the most commonly used temperature is 50 ± 3 ℃. However, when the temperature is high enough to make the drug play its maximum role, when the temperature is increased, the bactericidal effect is no longer improved. The determination of sterilization temperature is related to the following conditions:
1) temperature tolerance of the sterilized product.
2) Loading capacity and loading mode: the loading capacity is required to be ≤ 80%, without contacting the cabinet wall, and there is no less than 125px gap between the boxes.
3) Thickness, size and bulk density of packaging materials.
The water content of sterilized articles, the degree of drying of microorganisms and the relative humidity of environment all affect the sterilization effect of EO. When the relative humidity is lower than 30% RH, the sterilization effect is obviously affected. Therefore, wet microorganisms are easier to kill than dry ones, but the killing effect is not in a positive proportion to the relative humidity, the humidity is too high, EO is diluted and hydrolyzed. Therefore, the humidity after vacuumizing and before dosing should be controlled within the range of 30% RH ~ 80% RH.
The degree of pre vacuum determines the amount of residual air, and the amount of residual air affects the pressure after EO addition and the ease of moisture and heat entering the interior of the article, so the pressure, especially the pressure before humidification, has a great impact on the sterilization effect. The pressure setting should be based on the overall consideration of the sealing performance of the equipment around the bridge cutoff aluminum alloy doors and windows and the positive and negative pressure bearing capacity of the extinguished items. Within the range of equipment operation and the bearing capacity of the items, the negative pressure sterilization generally has a better effect than the positive pressure sterilization.
4. Ethylene oxide concentration
As an important factor affecting the sterilization effect, the sterilization effect can be improved by increasing the concentration. In a certain concentration range, when other conditions such as temperature and humidity are the same, with the increase of the concentration, the shorter the time required to kill a certain concentration of microorganisms, the better the killing effect.
Under the same conditions, the longer the sterilization time, the smaller the survival probability of microorganisms and the better the sterilization effect. Under the condition that other parameters are not changed except time, the shortest effective action time (half cycle) of ethylene oxide without viable bacteria is determined, and the specified action time of the process should be twice of the half cycle.
6. Determine process parameters
According to the above elements, determine the verification procedure and develop the process parameters.
As the most important low-temperature sterilization method at present, carbon dioxide + ethylene oxide mixed gas sterilization, under the premise of ensuring safety and environment, in strict accordance with operating procedures and technical specifications, improve process control, and achieve the safety and effectiveness of sterilization process.