Vinegar and Hydrogen Peroxide
According to the internet, the combination of vinegar and 3% hydrogen peroxide is supposed to to be more effective at germ-killing than either one by itself. So, I decided to test the combination. However, you are never supposed to mix vinegar and hydrogen peroxide in the same bottle. Mixing them forms peracetic acid which is corrosive and produces dangerous fumes. So, I kept the 3% hydrogen peroxide in its own brown spray bottle. I also put regular white vinegar in its own spray bottle.
First, I swabbed both sides of a dirty sink, and rubbed the swabs on agar plates.
Then I sprayed both sides of the sink with 3% hydrogen peroxide (40 sprays each). I completely covered the sink with 3% hydrogen peroxide. Then I held up a paper towel shield so I could spray just one side of the sink with 40 sprays of white vinegar.
After 10 minutes, I swabbed both sides of the sink and rubbed the swabs on agar plates.
Then I thoroughly rinsed both sides of the sink with clean tap water to remove the residual vinegar/hydrogen peroxide.
Then I swabbed both sides of the sink again and rubbed the swabs on agar plates.
I also did a negative control where I swabbed tap water and rubbed that on an agar plate. As expected, nothing grew.
As usual, the plates from before I rinsed the 3% hydrogen peroxide off the sink were very clean. This is because the hydrogen peroxide was picked up on the swab and traveled with the germs to the agar plate. However, the plates where I rinsed the hydrogen peroxide and vinegar off before I swabbed were not very clean. This means that the hydrogen peroxide/vinegar combo does kill some germs but not everything in a 10 minute period. The combo looks like it might be a little better at germ-killing than hydrogen peroxide alone, but the difference isn't that very significant my experiments.