At intervals during the incubation period and at its conclusion, the media are examined for macroscopic evidence of microbial growth. If the material being tested renders the medium turbid so that the presence or absence of microbial growth cannot be easily determined by visual examination, 14 days after the beginning of incubation, portions (each not…
The sterility test can be carried out by the following methods: Membrane Filtration Method: This method is employed if the test substance is any of the following: Procedure: Membrane filters of pore size not greater than 0.45 μm and diameter of 47 mm, which can retain microorganisms, are employed for the sterility test. The filtration system and…
The selection of samples and the number of samples to be taken from any given batch of sterile product are important. The material must be thoroughly mixed if the sample is to be taken from the bulk. The sample is taken at random from the batch of final containers.
The sterility test is based on the principle that when microorganisms are supplied with nutrient medium and incubated at favorable temperature conditions, the microorganisms will grow and multiply. The presence of microorganisms can be identified by the turbidity in the clear medium. Preparation of Culture Media The culture media used for the sterility test must…
Learning Objective Leak Test Sealing of ampoules may be done by tip sealing and pull sealing methods. During the sealing process there are chances that ampoules are incompletely sealed and cracks may occur around the seal or at the base of the ampoule as a result of improper handling. Hence, the leak test is intended…
Sterilization by radiation uses highly penetrable ionizing radiations such as gamma rays and cathode rays. The mechanism of sterilization is by alteration of the chemical components within or supporting the microorganism to form deleterious new chemicals capable of destroying the cell. These radiations also have the capability to destroy or disorient the cell’s vital structure…
Sterilization by gas can be effectively employed on materials, which are heat sensitive and moisture sensitive. The most frequently used gases for this purpose are ethylene oxide, propylene oxide, and formaldehyde. The gases mentioned are highly flammable in mixture with air, so they are diluted with an inert gas such as carbon dioxide or a…
This method of sterilization comes under the mechanical method of sterilization, whereby the microorganisms are physically removed by adsorption or by sieving mechanism onto the filter medium. Filtration sterilization can be effectively applied on heat-sensitive solutions. Filters that are available commercially come with various pore sizes. They are made up of thin plastic membranes of…
This method of sterilization is usually carried out in ovens such as hot air oven, which are normally heated by electricity or gas and are thermostatically controlled. The basic mechanism of sterilization by this process is dehydration of microbial cell wall followed by oxidation. Higher temperature and longer periods of exposure are needed in this…
The method of moist heat sterilization is based on the steam under pressure. An autoclave is used for this purpose. Moist heat sterilization is the method preferred for the pharmaceutical products that can withstand heat. Microorganisms are coagulated and destroyed at a lower temperature in the presence of water. The mechanism of microbial destruction in…