Quaternary Ammonium Compounds (QACs) are known for their bactericidal and disinfecting qualities. QACs are water-soluble and readily absorb on surfaces, leaving a protective barrier against microbiological growth. They are used extensively throughout the healthcare and food processing industries to sanitize, deodorize and disinfect surfaces and equipment. QACs are also routinely formulated with various water treatments to inhibit algal growth in cooling towers, humidifiers and swimming pools. These tests are applicable to the monitoring of QACs in cleaning solutions and in treated cooling waters.

CHEMetrics' method employs a titrimetric chemistry in which stabilized polyvinyl sulfate is the titrant and toluidene blue is the end point indicator. A color change from purple to navy blue signals the end of the titration. Results are expressed as ppm (mg/L) QAC.