Supercritical Fluid Extraction of Inorganics in Environmental Analysis

Abstract Supercritical fluid extraction (SFE) of metal ions via in situ chelation and preformed metal chelates using pure or modified CO 2 from several matrices has been accomplished. To understand the extraction results better, the solubilities of different ligands and metal chelates have been measured in supercritical fluids (SFs). In most cases, fluorinated chelates have been found to possess higher solubility in the SF than nonfluorinated ones, which in turn can often enhance extraction efficiency. Metal chelate stability under supercritical conditions plays an important role in the extraction of metals. Also, the matrix has a major effect on extraction efficiency of both hydrated metal ions and metal chelates. In order to obtain sufficient extraction not only should solubility of the metal complex be considered, but also the overall stability of the complex is critical.