Quats are used at what range and contact time?

• A. 50-99 ppm; 7 seconds
• B. 200-400 ppm; 30-60 seconds
• C. 12.5-25 ppm; 30-60 seconds
• D. 100-150 ppm; 5-10 seconds

Answer: (B)

Quats used as sanitizers must be applied at a sufficient concentration and given enough contact time to effectively inactivate microbes on surfaces. The standard sanitizing range for quaternary ammonium compounds is about 200 to 400 parts per million, with a contact time of 30 to 60 seconds. This combination ensures that the disinfecting molecules have enough presence on the surface for a long enough period to disrupt microbial membranes and achieve the desired reduction in contaminants. If the concentration is too low or the dwell time too short, microbes may not be fully inactivated, which is why the other options—lower concentrations or shorter contact times—are not adequate. Always follow the product label, and consider factors like temperature and organic matter, which can affect efficacy.