Detection of slightly soluble systems by means of organized media in flow-injection analysis

Species that are slightly soluble in water (reagents, analytes or reaction products can be used in hydrodynamic analytical systems by means of a judicious choice of an appropriate organized medium allowing one to operate in homogeneous media with the attendant advantages. In addition, these systems allow one to improve existing analytical methods and to develop new analytical procedures. Results obtained with two types of insoluble systems are presented: those provided by 1-(2-pyridylazo)-2-naphthol (PAN) and those originating from Arsenazo III in a strongly acid medium. Detection in these systems is possible by working with an organized medium. New methods for the determination of thorium, uranium and rare-earth elements are proposed.