They are not oxidizers, like chlorine, but are surface-active agents that breakdown the cell walls of microbes causing leakage of the internal contents. The organic groups can be similar or different in chemistry and structure, and the number of nitrogen atoms can vary. Any anion may be attached to the cation, but it is usually a salt formed with chloride or bromide. Classification and biological activity of the quaternary ammonium compounds depend upon the nature of the organic groups, the anion, and the number of nitrogen atoms present.
Quats are by nature wetting agents that foam and cling to vertical, radial, and underside surfaces.
They have excellent penetration properties, and are less affected by organic matter than chlorine. They leave a residual film that provides an extended residence time of biological activity. Quats are more stable and less corrosive than chlorine products, but more expensive. They may eventually corrode electronics, such as controls associated with sizing and grading equipment. Quats are low in mammalian toxicity and non-irritating to the skin.