Disinfection surface activity- effects

It is therefore apparent why the physical chemistry of surfaces and the structure and activity of surface-active agents are also of interest to the medicinal chemist. Antimicrobial detergents and many disinfectants exert their activity by interacting with biological surfaces and are important examples of surface-active drug effects. 

Although alcohols, as topical skin disinfectants, provide excellent immediate antimicrobial activity, they show little persistent activity. Once dried on the skin surfaces, antimicrobial effects of an alcohol have ended. Hence, their value as surgical hand scrub formulations and preoperative skin preparations where... 

Contain surface-active agents that act as solubilizers and lower the vapor pressure of iodine. lodophors have a deep amber color that fades with depletion of the available iodine. They react with organic matter, but then more free iodine is released. After 16 hr, a few B. sub-tilis spores remain after treatment with 100-200 ppm Wescodyne. Wescodyne diluted 1 to 10 with 50% ethanol has been recommended as a handwashing disinfectant but it is not effective against nonlipid virus, e.g., poliovirus 1 in 20% bovine serum albumin or rabbit blood nor would it be effective against spores (no organic matter present) (496). Inactivates poliovirus 1 in rabbit blood in 2 min. Useful for spills of nonlipid (resistant) viruses, especially spills in safety cabinets (496). 

A property common to the cationic surfactants is that their positively charged surface-active part is readily absorbed by the substrate which, in most cases, is negatively charged in water. This is the reason for their bactericidal action in disinfection and their conditioning effect on textile fibres. 

The threat of accidental misuse of quaternary ammonium compounds coupled with potential harmful effects to sensitive species of fish and invertebrates has prompted some concern. Industry has responded with an effort to replace the questionable compounds with those of a more environmentally friendly nature. Newer classes of quaternaries, eg, esters (206) and betaine esters (207), have been developed. These materials are more readily biodegraded. The mechanisms of antimicrobial activity and hydrolysis of these compounds have been studied (207). AppHcations as surface disinfectants, antimicrobials, and in vitro microbiocidals have also been reported. Examples of ester-type quaternaries are shown in Figure 1. 

Surface disinfectants Compounds containing phenolics, chlorhexidine (not effective against bacteria spores), quaternary ammonium salts (additional activity if bis-n-tributyltin oxide present), hypochlorites such as household bleach, alcohols such as 70-95% ethanol and isopropyl (not effective against bacteria spores), potassium peroxymonosulfate, hydrogen peroxide, iodine/iodophores, and triclosan. 

The membrane filtration technique is used once, prior to the introduction of a new disinfectant within the production department. The surface testing technique is used prior to any changes in the recommended procedure for evaluating its effectiveness on surfaces to be treated and demonstrating activity against contamination for various contact times. 

The effects of virucidal chemicals on VACV inactivation has been studied for several decades. Research investigating chemical disinfectants on surfaces for the prevention of disease spread has focused mainly on the healthcare and food industry [94], Discussed below are specific details, from studies, on the known or expected activities of major classes of chemical virucides against VACV. 

For final agricultural application, the concentrated product must be diluted with water to make a 2 % solution, which is applied with compressed air by hand held or power spray equipment. In the field, as shown in Fig. 6.6-37, the disinfectant solution surrounding the microcapsules evaporates, providing the disinfectant action. Then, the insecticide diffuses through the capsule wall and becomes available on the outside surfaces in small, highly effective amounts of the active substance. As the insecticide dissipates it is replenished by more chemical from the inside. Thus, the product is still working after most other insecticides have lost their effect. 

The production of glyphosate herbicide (Round-up), the world s most successful herbicide, is another example of utilization of the catalytic properties of carbon surfaces [338], The Monsanto process by which Round-up is produced uses activated carbon as an oxidation catalyst for one of the key synthesis steps. The catalyst is produced by the treatment of activated carbon with ammonia at a high temperature to impart the desired nitrogen functionality. These functionalities are also commercially important for the reduction of chloramine in potable (drinking) water. Since water utilities are increasingly using chloramine rather than chlorine for water disinfection, and standard activated carbon products are not effective for removal of residual chloramine (which, for example, is highly toxic to dialysis patients), a catalytic carbon must be used to reduce its content [339,340],... 

Household bleach contains sodium hypochlorite. A 1 10 dilution of bleach is effective for disinfection of a direct blood spill on a porous surface. In addition to inactivating HIV. sodium hypochlorite solutions have disinfectant activity against other viruses including hepatitis B virus. The answer is (D). 

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