Recent development of substoichiometry in trace analysis

A review of the substoichiometry in trace analysis is presented. The principle of the method: substoichiometric isotope dilution analysis, substoichiometric radioactivation analysis (direct method, the method of carrier amount variation and the comparison method) and the substoichiometry based on isotope exchange reaction (direct isotope exchange method and the reverse isotope exchange method) are outlined, the theoretical basis of substoichiometric extraction in chelate system is treated, the problem concerning the reproducibility and accuracy of the substoichiometric separation is discussed, and some practical applications are given. In the last part some recent developments are reviewed, e.g.: multielement substoichiometry, displacement substoichiometry, multiple isotope dilution method, ion-association extraction, coprecipitation separation etc. A tabulated summary of the data is given, together with 177 references. (T.G.)