Hydrion QT-40 Quaternary Test Paper provides a simple, reliable, and economical means to measure the concentration of Quaternary Sanitizers, particularly multi-quat broad range quaternary ammonium sanitizer solutions. With color matches at 0-150-200-400-500ppm (parts per million), the test paper measures concentrations between 0-500ppm, detecting exhaustion of solutions that should be replaced as well as helping to avoid using excessive amounts of sanitizing agents.