I will have to do some checking, but somewhere in the back of my mind I remember from one of my microbiology classes, that 70% alcohol had greater effectiveness as a bactericidal then 90+% alcohol. I am not sure I can find the reference, but will look around. I do know that a number of commercial disinfectants have narrow ranges at which they must be diluted for greatest cidal effect. More is not always better with disinfectants.

I looked our bottle of isopropyl alcohol at home and it was 91%. I also looked at a different brand of alcohol wipes and they were 70%.

The mystery continues. Pete