Analytical Chemistry of Phases of Variable Composition and the Principles of Stoichiographic Determination of Such Phases in Multielement Multiphase Samples

The general problems of determining the stoichiometry and content of solid phases of variable composition in multielement multiphase substances are discussed. The possibilities and conditions of application of a reference-free stoichiographic method based on the differential dissolution (DD) of components for the analysis of samples containing spatially homogeneous and inhomogeneous phases are considered. The results of mathematical modeling of the DD process for a mixture of phases of constant and variable composition are presented. These data substantiate the use of the stoichiogram affinity criterion for the identification of spatially inhomogeneous phases of variable composition. Examples of applying the DD method to the phase analysis of various substances containing phases of variable composition are given.