This is the method that manufacturers use to test efficacy, or effectiveness of bacteria death. This is where information comes from to write the label directions. (Please, please, please read label directions.) The method gives them information about how much active ingredient to put into their formulation.
At least one representative organism for each type organisms such as gram-negative rod and cocci and a gram-positive organism are tested. More information about types of bacteria later. For the curious, Wikipedia is a good place to start for information.
This test starts by growing each required organism in its own broth, (food supply). Dilutions are made of stock culture to determine the number of organisms present in the solution. A microscope slide that has grid lines is used to determine a count for the mathematical calculations based on the dilution of the stock culture and standard formula for the microscope grid.
Definition parts per million (ppm). If you understand percentages, you can understand ppm. Percentage is part of a hundred (100) while ppm is part of a million (1,000,000). Ppm allows for measuring smaller levels of a substance.
A typical level for an active ingredient is anywhere between 0-2500 ppms. Usually range finding is done by testing at a broad range and then narrowed down to closer approximate the test dosage.
The high level may or may not be set based on toxicity of the biocide. They are necessary to preserve shelf life and safety for the consumer. Remember biocides are killers of life. They should be handled with care and caution especially around children.
Every biocide has another chemical that will deactivate it for Chlorine it is sodium thiosulfate. You can purchase this online if you want to neutralize chlorine products before you dispose of them. It only takes a tiny bit (less than a teaspoon) to neutralize a whole bucket of bleach solution.
After the bacteria has been grown, it is inoculated into another solution containing the biocide. At specific time intervals such as 0.5, 1, 2, 3, 4, 5, 10 minutes a neutralizer is added to the inoculated biocide solution. The resulting solutions are then tested to determine the presence of live organisms. This is how the label directions are created and why it is important to follow them for complete killing of your pathogens.
Ph.Ds. please note that this is not intended to be a complete explanation of Anti-microbial testing only basic information for the lay person to understand how and why behind label directions. This information is based on my years of experience at a major biocide company. Many hours of laboratory work have preceded and followed the testing outlined above.
I hope this was informational and understandable for you.
Next up my favorite cleaning product Splash-less® Clorox®.
Label Translator 