Purell Hand Sanitizer Testing
Purell® Hand Sanitizing Gel
My husband helped me out with this experiment. After work, he pressed his dirty left hand onto an agar plate. I rubbed a large glob of regular Purell (with moisturizers and Vitamin E) all over his right hand. (His hands were visibly clean.) He held his hand up in the air for a minute to dry and then pressed it into another plate.
The Purell worked very well and just left 4 small colonies. I have done these experiments multiple times. There may be a few colonies on the sanitized hand whether using the spray or the gel if you miss a spot. It is very important to use lots of the sanitizer. Hand sanitizer gels like Purell not been shown to kill norovirus. I have a list of hand sanitizers that do kill norovirus on this page.
How well does regular Purell Hand Sanitizing Gel work on dirty hands?
To test how well Purell hand sanitizing gel works on visibly dirty hands, I tested my son Jon's hands after he had gotten them dirty in mud outside. He pressed his dirty right hand onto an agar plate. Then I rubbed a quarter sized drop of Purell all over his other hand. It did not appear to remove any dirt. We let his hand dry for 1 minute. Then he pressed the treated hand onto another plate.
There seems to be a slight improvement in the amount of bacteria on the treated hand but it is still very dirty. From all of my experiments, alcohol hand sanitizers can't seem to penetrate dirt. They don't do well on dirty hands with the exception of Zylast antiseptic hand sanitizer.
I tested Purell Advanced (70% ethanol) on dirty hands as well. These were not visibly dirty but the kids had been playing outside with rocks for an hour. So, there was a light coating of dust/dirt.
As you can see, the plain alcohol hand sanitizers cannot penetrate actual dirt. So, if you are at a park or on a picnic, wipe hands clean with a wipe and then use the hand sanitizer.