QACs are cationic salts of organically substituted ammonium compounds and have a fairly broad range of activity against microorganisms, although more effective against Gram-positive bacteria at lower concentrations than Gram-negative bacteria. They are considerably less effective against bacterial spores. QACs are sometimes classified as surfactants. An example is benzalkonium chloride. QACs are the most widely used of the non-oxidizing disinfectants in the pharmaceutical industry. Their mode of action is on the cell membrane which leads to cytoplasm leakage and cytoplasm coagulation through interaction with phospholipids.
Quats are used in a variety of products and processes, including cleaning products, water purification, wood preservation and textile manufacturing.