Moist heat tests

Hospital sterilizer loads vary in composition, thus the challenge presented to the test organism can vary considerably, depending on the type and contents of packages in which they are placed. The benefits of a standardized test-pack constmction and test protocol are obvious, and such recommendation is made by AAMI for steam and ethylene oxide sterilizers (11). More recentiy in European (CEN) and International (ISO) standards, biological indicators are considered as additional information supplemental to the measurement of physical parameters. Indeed, for sterilization using moist heat (steam), the biological indicator information is not considered to be relevant. 

Aseptic BPS machines are subject to steam-in-place sterilization following standard CIP cycles. The SIP cycles are routinely measured by thermocouples located in fixed positions along the product pathway. Validation of SIP cycles should be carried out to demonstrate that consistent sterilization temperatures are achieved throughout the equipment to prove that the system can be effectively sterilized. Validation should also identify suitable positions for routine use, or justify the fixed probe positions already in place. The SIP validation is generally carried out with the help of additional thermocouples and should include the use of biological indicators (appropriate for moist heat sterilization). Test locations should include areas which may be prone to air or condensate entrapment. An accurate engineering line drawing of the system to aid identification of suitable test locations and document test locations selected should be available. 

The medium is then sterilized to eliminate all living organisms in the vessel.,The most common method of sterilization is by moist heat (steam under pressure) in an autoclave. Generally, the autoclave is operated at approximately 15 psi at 121°C. The time of sterilization depends on the nature of the material, the type of container, and the volume. For example, test tubes of liquid media can be sterilized in 15 to 20 minutes at 121 °C. 

Medium for use in a process simulation test can be rendered sterile using either moist heat (autoclaving) or filtration. The method chosen depends on the availability of suitable equipment and the information desired from the study. 

Since the direct estimation of microbial numbers by conventional culturing methods is time-consuming and well affected by environmental conditions (18), a simple test for the most resistant enzyme activity is appropriate on a routine basis. If enzyme activity is detected, it can be assumed that the heat treatment was inadequate (4,15). Appropriately, GFPuv can be employed as a BI in thermal processes (blanching, pasteurization, disinfection) at temperatures >75°C for products at pH > 5.5, with the inactivation of GFPuv shown to be directly related to the time of exposure to moist heat and pH. 

The manufacture of parenteral products is focussed at all times on the requirement for sterility of the finished product. Despite the fact that the regulators are clear in their preference for products to be terminally sterilized, the vast majority of parenterals are filtered through sterilizing grade filters and filled aseptically, primarily because stability considerations preclude the use of moist heat sterilization. The statistical limitations of sterility testing a sample... 

Sterilization by moist heat is suitable only for water-wetable materials and aqueous solutions. Both temperature and pressure should be used to monitor the process. The temperature recorder should normally be independent of the controller, and there should be an independent temperature indicator, the reading from which is routinely checked against the chart recorder during the sterilization period. For sterilizers fitted with a drain at the bottom of the chamber, it may also be necessary to record the temperature at this position, throughout the sterilization period, here should be regular leak tests on the chamber when a vacuum phase is part of the cycle. 

Geobacillus stearothermophilus is a thermophile and grows at temperatures between 50 °C and 65 °C. It is used as a test organism (biological indicator) to verify the efficacy of moist heat sterilisation processes. 

The experimental conditions necessary for the preparation of a solution of a diazonium salt, diazotisation of a primary amine, are as follows. The amine is dissolved in a suitable volume of water containing 2 5-3 equivalents of hydrochloric acid (or of sulphuric acid) by the application of heat if necessary, and the solution is cooled in ice when the amine hydrochloride (or sulphate) usually crystallises. The temperature is maintained at 0-5°, an aqueous solution of sodium nitrite is added portion-wise until, after allowing 3-4 minutes for reaction, the solution gives an immediate positive test for excess of nitrous acid with an external indicator—moist potassium iodide - starch paper f ... 

For each specific appHcation of a mbber compound as an iasulating material, there is a minimum value of resistivity below which it does not function satisfactorily. In addition, iasulating compounds are required to withstand the effect of water, moist atmosphere, or heat without their resistivity values falling below a satisfactory level. Insulation resistance measurements frequently serve as useful control tests to detect impurities and manufactuting defects ia mbber products. 

Mayrhofer Stability Test. A modification of the Bergmann-Junk Test (see Vol 2, B102-R) for testing the stability of NC and propellants. Mayrhofer recommended the use of 20ml of a 2% Kl soln instead of w for the quant collection of decompn products. He also tested NG contg propints in both dry and si moist states, and found that while a stable sample behaved in a similar manner whether heated dry or moist, an unstable powd decompd rapidly in the presence of traces of w. Tonegutti (Ref 3) considered this test reliable for ballistites and unreliable for cordites... 

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