70%
70% isopropyl alcohol is by far better at killing bacteria and viruses than 99% isopropyl alcohol. As a disinfectant, 70% concentration of alcohol is the most effective at killing pathogens. Any higher or lower percentage will be less effective.
Ethyl alcohol, at concentrations of 60%–80%, is a potent virucidal agent inactivating all of the lipophilic viruses (e.g., herpes, vaccinia, and influenza virus) and many hydrophilic viruses (e.g., adenovirus, enterovirus, rhinovirus, and rotaviruses but not hepatitis A virus (HAV) 58 or poliovirus) 49.
A 60% - 80% concentration of ethanol or isopropyl alcohol has been demonstrated to be the most effective.
You can buy rubbing alcohol with a concentration of 70% or 99% isopropyl alcohol. Even though you may think the higher concentration is more effective, experts say 70% is actually better for disinfecting. It has more water, which helps it to dissolve more slowly, penetrate cells, and kill bacteria.
Ethanol solution is used widely as a disinfectant in cell culture room at two usual percentages, which are 70% and 75%. The experimenter often sprays it on experimental tools, on gloves, lab coat, and over other necessary experiment items.
l6 Enteric bacteria such as Escherichiu coli are relatively sensitive and grow very little in ethanol concentrations above 6% by volume. Z. mobilis, an obligate ethanol producer, is considerably more resistant to ethanol with little growth above 9% ethanol by volume.
High concentrations of ethanol are bactericidal; however, bacteria can grow in the presence of low concentrations of ethanol (21, 22).
An ethanol solution of around 70 % (v/v) is commonly used to induce DNA precipitation. 1 A decrease in ionic dissociation at lower dielectric constants in the presence of ethanol is considered to be the mechanism that underlies DNA precipitation.
70% Ethanol
Aqueous alcohol solutions are not appropriate for surface decontamination because of the evaporative nature of the solution; a contact time of ten minutes or more is necessary and not achievable using a 70% (v/v) aqueous solution of ethanol.
A lower percent alcohol means there's more water diluting the mix in the bottle. But according to microbiology, 70 percent alcohol is probably more effective than 91 percent for disinfecting—depending on what kind of germs you're trying to kill.
Mixtures that contain at least 70% alcohol are best if they can be sourced, and these mixtures can neutralize viruses and other bacteria on a surface if left wet for at least 30 seconds.
To prepare 1 liter of 70% Ethanol using 95% lab Ethanol add 740ml of lab ethanol to 260ml water. Sodium hypochlorite (bleach) solutions are unstable.
The group of Gram-negative bacteria capable of oxidising ethanol to acetic acid is called acetic acid bacteria (AAB). They are widespread in nature and play an important role in the production of food and beverages, such as vinegar and kombucha.
70% denatured alcohol 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.
Increased ethanol concentration in the nutrient medium gradually slowed down the growth of Escherichia coli cells. However, during growth in the presence of 5% ethanol, DNA synthesis per cell increased about 2.5-fold compared to control cells.
Alcohol concentrations lower than 40% were found to be significantly weaker in affecting bacterial growth.
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.
Does alcohol kills germs and viruses? Isopropyl alcohol is effective against viruses such as FCV at 40% – 60% concentrations. Ethanol however, is more effective at 70% – 90% concentrations against FCV.
At a BAC of 200% to 400%, patients develop nausea and vomiting, hypothermia, dysarthria, amnesia, diplopia, and nystagmus. With a BAC of greater than 400%, patients can develop respiratory depression followed by coma and even death.
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.
The concentrations of ethanol and methanol ranging from 2.5% to 0.15% concentration were well-tolerated by cells with respect to proliferation. Depending on the extracts or agents, each should be diluted in the suitable vehicle at the proper concentrations.
All cells were killed by a 15-s exposure to 30–40% ethanol while a concentration as low as 15–20% gave a total response after 5–10-min exposures.