Sterilization of materials

The first EtO commercial application was related to spices sterilization and/or fumigation. Phillips and Kaye conducted a series of studies using EtO, focusing on the sterilization of material with thermal resistance problems. 

Principally, three types of radiation are adequate for the sterilization of materials ultraviolet and gamma radiation. In the case of the radiation treatment of materials with ionizing (mostly gamma) radiation, a high exposure dose is necessary. Often a cobalt bomb (radioactive Co) is used for this purpose. The efficiency depends on the penetration depth. This procedure is adequate for the sterilization of plastics and other sensitive materials (e.g., for surgical purposes), as well as for foodstuffs (in Germany, only for spices). Metals or mineral materials only become germfree on the surface. 

Several methods have received considerable research attention as alternatives to salt curing. These include use of sodium bisulfite as a disinfectant to allow preservation with or without decreased salt in a brine cure use of disinfectants such as quatenary amines for temporary preservation in direct shipping to the taimery from the packing plant (see Disinfectants and antiseptics) preservation of hides by radiation sterilization (see Sterilization techniques) and substitution of materials such as potassium chloride for sodium chloride. These methods have found only limited commercial success. 

Incineration may be thought of as the complete destruction of materials by heat to their inert constituents. This material that is being destroyed is the waste product (i.e., the sludge). Sewer sludge as sludge cake normally contains from 55 to 85% moisture. It carmot burn until the moismre content has been reduced to no more than 30%. The purpose of incineration is to reduce the sludge cake to its minimum volume, as sterile ash. There are three objectives incineration must accomplish ... 

Packaging Similarly, information on the closure/packaging systems must be provided in terms of material specification, suitability/compatibility with the pharmaceutical product, dimensional specifications, water impermeability, and so on. Defence against microbial contamination should be discussed in the context of either packaging of sterile product or use of preservatives as appropriate. 

Production and service provision - Operate production and service provision under controlled conditions, maintain batch records, validation processes that cannct be verified, maintain identification and traceability of materials, address specific requirements for sterile products, provide suitable conditions for storage and distribution... 

Sterilization is an essential stage in the processing of aity product destined for parenteral administration, or for contact with broken skin, mucosal surfaces or internal organs, where the threat of infection exists, hi addition, the sterilization of microbiological materials, soiled dressings and other contaminated items is necessary to minimize the health hazard associated with these articles. 

Low-temperature steam with formaldehyde is of value in the disinfection/sterilization of some heat-sensitive materials (see also Chapter 20). 

Another issue in the preparation of reference material is the required shelf life. The shelf life of reference material is the time that it remains stable under proper storage conditions. Depending on the nature of the mechanisms affecting the stability of the material, various actions can be taken to improve the shelf life. Reduction of the moisture content is one of the first options to be considered. In many cases, moisture plays a key role in mechanisms leading to instability of the matrix and/or parameters. In other cases, sterilization or pasteurization of the material might be considered in order to stop bacterial activity. When preparing solutions, additives may increase the shelf life. Obviously, the shelf life of material is also a function of the storage conditions. 

Ozone can also be used as an oxidizing agent, but because of its instability, it must be generated on-site. It is a powerful oxidant for some organic materials, but others are oxidized only slowly or not at all. Ozone is only suitable for low concentrations of oxidizable materials. A common use is for the sterilization of water. 

Lewis, K. and Klibanov, A.M. (2005) Surpassing nature rational design of sterile-surface materials. Trends in Biotechnology, 23, 343—348. 

For protein-based drugs, filtration via a 0.2 pm filter is an effective way to achieve sterilization. Factors that determine the filtration efficiency include integrity of the filter, pressure, temperature, how rate, contact time of material with the filter, pH, and viscosity. Validation of filters should include chemical compatibility of the filter with the product and possibility of contaminant from the filters leaching into the product. 

Early separators used in NiCd cells for space applications consisted of materials as ordinary as Whatman filter paper and eventually nonwoven nylon felt (Pellon 2505). Pellon 2505 was more stable than cellulosic separators, but it too had stability limitations. In the late 1960s and early 1970s, nonwoven polypropylene saw limited use in NiCd cells. The PP separators were quite useful where sterilization (heating the cell to 135 °C) was required.The major difficulty with nonwoven polypropylene was that it was only marginally wet-table. and the amount of electrolyte that can be placed in the cell was limited. 

Fig. 16.42 Atrazine degradation in sterilized aquifer material (Al, Bl, Cl) and in natural (unamended) aquifer material (A2, B2, C2) for reactors under stagnant (15°C), stagnant (25°C), and recirculating (15°C) conditions. Data points are the mean of three replications. The least significant difference between these treatments at the p < 0.05 level is 0.075. Figures are identified as (A) Topeka, (B) Ashland, and (C) Hutchinson aquifers. (Schwab et al. 2006)...

During the development of a sterile formulation of pirlimycin, a semisynthetic, veterinary lincosaminide antibiotic derived from lincomycin 4, three lots of material were subjected to thermal stress at 40°C for a period of 4 months, which led to the observation of a previously unreported degradant present at 0.2% [69]. 

Where sterilization of starting materials is required, it should be carried out, where possible, by heat. Where necessary, other appropriate methods may also be used for inactivation of biological materials (e.g. irradiation). 

A laboratory must provide adequate and, if necessary, separate space for the performance of routine and specialized procedures. Examples of specialized procedures include aseptic surgery, necropsy, histology, radiography, handling of biohazardous materials, and cleaning and sterilizing of equipment and supplies. 

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