What is the required concentration for quaternary ammonium sanitizer?

• A. 500 mg/L
• B. 50 mg/L
• C. 1000 mg/L
• D. 5 mg/L

Answer: (A)

Quaternary ammonium sanitizers must be used at a specific strength to effectively reduce microbes on food-contact surfaces. The correct concentration is 500 mg/L because this level is within the typical range used to achieve sanitization within the standard contact time and without leaving excessive residue. Using too low a concentration, such as 50 mg/L or 5 mg/L, would not reliably sanitize. A much higher concentration, like 1000 mg/L, is usually unnecessary, can increase residue risk, and may exceed product label recommendations. Always follow the sanitizer’s label for the exact concentration, but in this context 500 mg/L is the standard target.