STERILISING AGENT

Titanium dioxide has also been involved in the photocatalysis of toxic inorganic substances to yield harmless or less-toxic species. Sterilisation of drinking water by chlorine yields potentially carcinogenic compounds so that ozone has been used as an alternative sterilising agent. Bromate... 

Figure 8.1. Biofilms are microbial communities that are made up of several species and often possess a distinct spatial structure. It has been found that living in a biofilm can offer significant protection to individuals, with sterilisation agents and even antibiotics being less potent against individuals if they are found in a biofilm. This is significant because it has been estimated that nearly three quarters of bacterial infections involve microbes that live in biofilm communities. Although there is a growing literature on the effects of NPs on biofilms, there is currently little knowledge of the production and metabolism of NPs in biofilms.

Sulfur has a very important role in the chemical industry. The vast majority of sulfur is used to produce perhaps the most important industrial chemical, sulfuric acid. Sulfur is also used to vulcanise rubber, a process which makes the rubber harder and increases its elasticity. Relatively small amounts are used in the manufacture of matches, fireworks and fungicides, as a sterilising agent and in medicines. 

Human eye tissue is usually analysed for the presence of zinc salt (sterilising agent) content after acid digestion in a microwave oven at elevated temperature and pressure. This solution can also be used for analyses of other metals for medical management and post mortem studies. 

In the food industry such equipment would use either a presterilised web exposed by a removable peelable layer, or UV or hydrogen peroxide as an on-line surface sterilising agent. Currently none of these would be acceptable for a pharmaceutical operation, although use for sterile oral liquids might bear consideration. 

Holah et al [1994] have drawn attention to the fact that disinfection or sanitation are an essential part of the cleaning requirements for food processing equipment to maintain product quality. Ozone has been suggested as a possible sterilising agent in the cleaning of heat exchangers [Bott 1991]. The ozone in... 

The items to be sterilised, other than products in sealed containers, should be wrapped in a material which allows removal of air and penetration of steam but which prevents recontamination after sterilisation. All parts of the load should be in contact with the sterilising agent at the required temperature for the required time. 

In the case of terminally sterilised products, from representative sites within the steriliser, including the sites shown by validation studies to be least accessible to the sterilising agent except that samples may be taken representatively from across each sterilising lot if ... 

Sterilisation can be affected by moist or dry heat, by ethylene oxide (or other suitable gaseous sterilising agent), by filtration with subsequent aseptic filling into sterile final containers, or by irradiation with ionising radiations (but not with ultraviolet radiation). Each method has its particular applications and limitations. Where possible and practicable, heat sterilisation is the method of choice. 

The D-value is used to describe the resistance to a sterilising agent. This is the time taken to produce a 90% reduction in viable cells i.e. the time corresponding to the 10 fraction in Figure 1, when using a fixed temperature or radiation dose. 

Allergic sensitivity to it was first reported by Feinberg and Watrous (1945), who elicited positive reactions to scratch tests in sensitised pharmaceutical workers. Rhinitis and asthma in subjects exposed to it as a sterilising agent is reported by Bourne et al. (1979). They elicited positive type I reactions to skin prick tests with unconjugated materials. 

Steam condensate. Although derived from a sterile source, condensate becomes contaminated when in contact with the process materials. Even when the steam is used as a sterilising agent, there is inevitably an initial or sustained discharge of condensate which can carry a substantial bioburden. For this reason, such condensate should be regarded as hazardous effluent, and be contained and treated as process waste. 

Heat as a sterilising agent is the method of choice for most effluent treatment plants, for a number of reasons ... 

An alternative to steam sterilisation is the chemical cold sterilisation of surfaces with vaporised hydrogen peroxide (VHP) (Figure 14.16). Hydrogen peroxide vapour is used here as the sterilisation agent. 

Like other bleaches, chlorine water also acts as a sterilising agent— it kills bacteria and other germs. 

Operation, Because the sterilising agent is a gas, it obviously must not gain access to the samples being tested or to any liquids in which it may dissolve and react therefore, all samples and culture media must be in sealed containers—the latter in screw-capped bottles. All outer surfaces must also be clean and grease-free otherwise organisms might be protected from the action of the ethylene oxide. 

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