Abstract: A method for detecting the presence of an infection in a liquid sample comprising the steps of: lowering the pH of the liquid sample so as to drive fatty acids present in the liquid sample to the gaseous phase; detecting fatty acids, ammonia and, optionally amine species present as gases in a headspace associated with the liquid sample using a detector which is sensitive to the presence of fatty acids, ammonia and, optionally, amine species; and correlating the presence of detected fatty acids, ammonia and, optionally, amine species with the presence of the infection.