All of the following may be used for chemically sanitizing food contact surfaces except:

Chemically sanitizing food contact surfaces is a critical practice in food safety, and certain substances are designated for this purpose because of their effectiveness in eliminating pathogens. Quaternary ammonium, chlorine, and iodine are all recognized sanitizers and are widely used in food service environments to ensure surfaces are safe for food handling. They possess antimicrobial properties that help reduce the number of harmful microorganisms on surfaces.

On the other hand, a degreaser is a cleaning agent specifically formulated to remove grease and oils. While it may be effective for cleaning, it is not a sanitizer and does not possess the same antimicrobial properties that are essential for reducing pathogens on food contact surfaces. Therefore, it does not qualify as a chemical sanitizer, making it the correct answer in this context. Understanding the functions of sanitizers versus cleaners is crucial for proper food safety practices.