At a 70% concentration, however, the ethanol takes longer to evaporate and this longer contact time means that it is able to penetrate cells more effectively. The water in a 70% grade is also important in denaturing proteins. And 70% ethanol also tends to be cheaper and is less flammable [1].Basically, a 90 or 91 percent alcohol solution is too powerful in some cases: It fries the outside of the cell before it can get into the inside and kill the actual germ. 70 percent alcohol is just the right proportion of water and alcohol to zap the entire cell.Alcohol is often used to disinfect small surfaces (e.g. rubber stoppers of multiple-dose medication vials, and thermometers) and occasionally external surfaces of equipment (e.g. stethoscopes and ventilators).

What kills streptococcus bacteria on surfaces : Also disinfect frequently touched surfaces, such as cell phones, keyboards, and toilet handles by using disinfectant sprays or wipes. If you do not have either, make your own disinfectant by mixing isopropyl alcohol (60% or more) with distilled water.

Why 70% alcohol is more effective as a disinfectant than 95% or 100% alcohol

First, it has been found to be more effective at killing microorganisms than higher concentrations of isopropyl alcohol. This is because the water content in the 70% IPA solution allows for better penetration into the microorganisms and denaturation of proteins.

Why is 100% alcohol not used for sterilization : Alcohols are not recommended for sterilizing medical and surgical materials principally because they lack sporicidal action and they cannot penetrate protein-rich materials.

99% isopropyl alcohol is used: To act as a solvent, a general-purpose cleaner's ingredient, or to clean surfaces. 99% isopropyl alcohol won't corrode metals or plastics, so it can be used extensively on all surfaces without leaving stains, including glass and screens.

70% IPA solutions penetrate the cell wall more completely which permeates the entire cell, coagulates all proteins, and therefore the microorganism dies. Extra water content slows evaporation, therefore increasing surface contact time and enhancing effectiveness.

Why is alcohol the best disinfectant

Alcohol-based hand antiseptics mostly contain isopropanol, ethanol, n-propanol, or a mixture of these as their active ingredients. The antimicrobial activity of alcohols is attributed to their ability to denature and coagulate proteins. This causes microbes to lose their protective coatings and become non-functional.Solutions of 70% IPA in water should be left on surfaces for 30 seconds to ensure disinfection. Pure (100%) IPA evaporates too quickly for such use and is less effective.There are other ways you can sanitize your brush. Boiling in hot water for three minutes works, however, you need to realize that if you boil your toothbrush, you will ruin it over time, and you will need to change toothbrushes more often.

Since a 70% ethanol solution has more water, it takes longer to dissolve and thus can actually penetrate the bacterial cell wall and kill it.

Why is 100% ethanol not used : Therefore, the ethanol has to pass the bacterial membrane/wall to get into the bacteria – if you use 100% ethanol instead, the bacteria get 'sealed' and they will survive… Another mechanism is the high osmotic pressure of ethanol/water-mixtures; and the 70% has the highest one.

Is 100% isopropyl alcohol possible : While the concentration of isopropyl alcohol is 100%, the concentration of many brands of rubbing alcohol is 70%. The difference in strength makes rubbing alcohol safe to use in the home to disinfect objects and scrapes on the skin.

Why is 70% ethanol used not 100%

100% ethanol completely coagulate the outer cells proteins and it works as defense mechanism in the cells of organism but in case of 70% ethanol, the ethanol does not completely coagulates the proteins of the cell hence penetrates in the organisms body and it dies. So the area becomes contamination free.

70% IPA solutions penetrate the cell wall more completely which permeates the entire cell, coagulates all proteins, and therefore the microorganism dies. Extra water content slows evaporation, therefore increasing surface contact time and enhancing effectiveness.100% ethanol completely coagulate the outer cells proteins and it works as defense mechanism in the cells of organism but in case of 70% ethanol, the ethanol does not completely coagulates the proteins of the cell hence penetrates in the organisms body and it dies. So the area becomes contamination free.

Should I throw away toothbrush strep : When you have strep or a garden-variety sore throat, after you're feeling better you should toss your toothbrush and buy a new one. A fresh tool will have no germs. It came from a sterile environment. So you won't re-infect yourself.