Effective sanatizing using alcohol is at higher percentages such as 60-70%. However stores are running low and what is left over in high supply is the 50% isopropyl. 50% means that half the bottle is alcohol and half the bottle is water. When you have no other option your going to have to buy the 50% bottle and then concentrate it. My question is how can you make the percent of alcohol higher or in chemistry we say "concentrate the solution". Remeber earlier in the year we said that boiling is a seperation technique, however alcohol boils before water and would only decrease the percent of alcohol. Attach your solution along with proof that you found on the internet that would effectivly save you money and make better alcohol than the competitors.