Samples sterilization

The coefficients A, B, and C are fitted using a least-squares approach. Results from this approach are given in Table 6. Each data point for the occluded moisture at a given time is a mean value of at least six assays from samples sterilized and dried in different locations within the autoclave. The model predicts mean moisture values within the 95% confidence interval of the measured mean moisture values. Using the data in Table 6 we selected 12 h as the time required to adequately dry the stoppers, since 16 h did not offer a significant decrease in moisture over the 12-h results. 

Sterile Sample+Sterilizer (HgCl2) abiotic sterile degradation... 

The agar [9002-18-0] plate method consists of adding a known quantity of sample, usually 1.0 or 0.1 mL, depending on the concentration of bacteria, to a sterile petti plate and then mixing the sample with a sterile nutrient medium. After the agar medium solidifies, the petti plate is incubated at 32°C for 48 hours after which the bacterial colonies are counted and the number expressed ia terms of a 1 mL or 1 g sample. This procedure measures the number of viable organisms present and able to grow under test conditions, ie, 32°C. 

Bacteriological sampling is performed by manual techniques because of stringent sterilization requirements. Samples are taken in wide-mouthed, sterile, glass-stoppered bottles that are wrapped in paper prior to sterilization in an autoclave at 138 kPa (20 psi) or in an oven at 170°C. The botde is unwrapped and the lower portion is held in the hand. The sample is taken with the botde mouth in the direction of the flow. The stopper must be protected from contamination, the botde only partially filled, and the sample stored at 4°C after sampling. For bacteriological samples withdrawn from a tap, the water should mn for five minutes and then be shut off the tap should then be sterilized by flaming before a sample is taken. 

Another standard test, which is much simpler and more convenient, is the membrane filter technique. A suitable volume of sample is filtered through a sterile, 0.45-p.m membrane filter. The filter is placed in a petri dish containing a specific growth medium (M-Endo nutrient broth, M-Endo medium) and incubated for 24 h at 35°C. If after this time the colonies show the characteristic green sheen, this is taken as positive evidence for the presence of the coliform group (see Water, sewage). 

For MPN determination, sterile pipettes calibrated in 0.1-ml increments are used. Other equipment includes sterile screw-top dilution bottles containing 99 ml of water and a rack containing six sets of five lactose broth fermentation tubes. A sterile pipette is used to transfer 1.0-ml portions of the sample into each of five fermentation tubes. This is followed by dispensing 0.1 ml into a second set of five. For the next higher dilution (the third), only 0.01 ml of sample water is required. This small quantity is very difficult to pipette accurately, so 1.0 ml of sample is placed in a dilution bottle containing 99 ml of sterile water and mixed. The 1.0-ml portions containing 0.01 ml of the surface water sample are then pipetted into the third set of five tubes. The fourth set receives 0.1 ml from this same dilution bottle. The process is then carried one more step by transferring 1.0 ml from the first dilution bottle into 99 ml of water in the second for another hundredfold dilution. Portions from this dilution bottle are pipetted into the fifth and sixth tube sets. After incubation (48 h at 35 C), the tubes are examined for gas production and the number of positive reactions for each of the serial dilutions is recorded. 

Both openings of the flask are stopped with cotton wool and the medium is sterilized by placing it in an autoclave for 30 minutes at 120°C. The flask is then cooled to 29°C to 30°C and a small sample is taken to check the sterility and the pH value which should be approximately 5. 

As described in U.S. Patent 2,916,485 12 liters of a nutrient medium having the following composition is placed in a 30 liter fermentor equipped with stainless steel fittings including sparger, impeller, baffles and sampling lines and the medium is sterilized by heating at 121°C for two hours. 

EC verification provides an alternative to the model of establishing a certified production QA system. Independent testing of either all devices, or a statistically representative sample of each batch, is conducted by or on behalf of the Notified Body, which then issues a certificate of conformity for the tests conducted. This is not a popular option due to the costs involved. The procedure is not capable of providing adequate assurance as to the sterility of devices. Instead, an assurance of sterility must be based on the application of a production QA system to the sterilisation process. 

Sample Collection and Enzyme Stability. Serum samples are collected with chemically clean, sterile glassware. Blood is allowed to clot at room temperature, the clot is gently separated from the test tube with an applicator stick, and the blood is centrifuged for 10 minutes at 1,000 g. If the red cells are known to contain the enzymes whose activity is being measured, as in the case of LD, even slightly hemolyzed serums must be discarded. When acid phosphatase is to be measured, the serum should be placed immediately in ice and processed as soon as possible, or it should be acidified by the addition of a small amount of sodium citrate. Anticoagulants such as EDTA, fluoride and oxalate inhibit some serum enzymes. However, heparin activates serum lipoprotein lipase. 

For parenteral use, the antibiotic is packed in sterile vials as a powder (reconstituted before use) or suspension. For oral use it is prepared in any of the standard presentations, such as film-coated tablets. Searching tests are carried out on an appreciable number of random samples of the finished product to ensure that it satisfies the stringent quahty control requirements for potency, purity, freedom horn pyrogens and sterility. 

A sterility test is basically a test which assesses whether a sterilized pharmaceutical or medical product is free from contaminating microorganisms, by incubation of either the whole or a part of that product with a nuhient medium. It thus becomes a destructive test and raises the question as to its suitability for testing large, expensive or delicate products or equipment. Furthermore, by its very nature such a test is a statistical process in which part of a batch is randomly sampled and the chance of the batch being passed for use then depends on the sample passing the sterility test. 

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