What must a food handler use to determine the concentration of sanitizing solution?

He must test the solution with a sanitizer kit.

Explanation:

The concentration of sanitizing solution must be tested with a sanitizing kit. It is composed of disinfectant test strips that measure the sanitizing solution concentration. A very important part of the daily operation of a food establishment is the proper disinfection of the equipment.  Generally, chlorine is used to disinfect multipurpose utensils, food contact surfaces and other food preparation items. Over time, the concentration of chlorine decreases due to volatile elements.

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catya your not at all which answer i've seen you do this on another question!