Advances in quaternary ammonium biocides

AbstractSeveral generations of structurally variable quaternary ammonium biocides were developed from approximately 1935 until the present. Demand for products with improved microbiological performance guided each successive step of development. Commercial availability of dialkyl dimethyl ammonium chlorides in 1965 set the stage for significant advances in quaternary biocide practices in the USA and Europe. This trend is continuing today with development of new, fourth‐generation quaternary biocides. Regulatory requirements by the US Environmental Protection Agency (organic soil tolerance) and specific consumer/marketing demands (hard water tolerance) provided a renewed challenge for quaternaries meeting those requirements. Development and properties of new, fourth‐generation quaternary biocides meeting those challenges are discussed. Some of the functional advantages of quaternaries are outlined. Development of the fourth‐generation quaternary biocides has led to products demonstrating significantly superior broad spectrum biocidal activity, specifically designed to meet the new challenges of organic soil and hard water contamination. Strong market gains, made by quaternary biocides over the recent past, have been primarily as a result of the type of work described herein, but some of the gains in quaternary usage can be ascribed to concern over adverse toxicological and environmental impact of other traditional biocides such as phenolics and aldehydes. The outlook for a continued increase in the use of modern‐day quaternary biocides is encouraging.