It’s around every corner and in every backpack and purse. And – after the initial buying panic this spring – it’s even back on your local grocery store shelf! With flu & cold season around the corner and the Covid pandemic continuing you’re likely to use these gels this fall. So why not learn a little about their biology and chemistry?
The major and only active ingredient is most hand sanitizers is alcohol. Either isopropyl alcohol, ethanol, n-propanol, or some combination of the three. (There are also non-alcohol versions that contain antibiotics like benzalkonium chloride or triclosan but these are less effective and less popular.)
Hand sanitizers ideally have a high, but not too high, alcohol content, so water is also present as a diluting agent. This is because concentrations lower than 60% lack the potency needed to kill the majority of germs on a surface but concentrations higher than 80% evaporate too quickly.
Most store-bought sanitizers also have a gelling agent. This serves two purposes. The first is to further slow evaporation and thus maximize the time the alcohol had to work against any microbes. The second is convenience – gels are easier to dispense on the go.