Chlorine test strips for food; 0-200ppm. Chlorine test strips can confirm that your cleaning solution (bleach) is strong enough to disinfect cutting boards & tools used in food preparation. These bright white strips change color to different shades of purple to indicate a strength of 10, 50, 100 or 200ppm. An inexpensive way to avoid food poisoning & lawsuits! These chlorine test strips will determine in seconds whether your cleaning solution of bleach is a safe 200ppm or close to inactive at 10ppm. 100 strips per pack.