Chelate-assisted solvent-extraction

Percent extracted (key equation 18.10), p. 543 Solvent extraction of metal ions-complexes, chelates, p. 544 Accelerated and microwave-assisted solvent extraction, p. 546 Solid-phase extraction, p. 547 Solid-phase microextraction, p. 551... 

A procedure was developed for the determination of total and labile Cu and Fe in river surface water. It involved simultaneous solvent extraction of the metals as diethyldithio-carbamates (ddc) and tfac complexes. The complexes were extracted by isobutyl methyl ketone (ibmk) and the solution subjected to flame atomic absorption spectrometry. Variables such as pH, metal complex concentration, reaction time, ibmk volume and extraction time were optimized. Prior to the solvent extraction a microwave-assisted peroxydisulfate oxidation was used to break down the metallorganic matter complexes in the river surface waters . Trifluoroacetylacetone was used as a chelation agent for the extraction and quantitative determination of total Cr in sea water. The chelation reaction was conducted in a single aqueous phase medium. Both headspace and liquid phase extractions were studied and various detection techniques, such as capillary GC-ECD, EI-MS (electron-impact MS) and ICP-MS, were tested and compared. The LOD was 11-15 ngL Cr for all the systems examined. The method provided accurate results with EI-MS and ICP-MS, while significant bias was experienced with ECD °. ... 

The characteristics of di- and trialkyllead species (salts) do not allow these to be directly extracted by any organic solvent, but chelating agent assisted extraction gives better results. Dithizone, diethyldithiocarbamate (DDTC) and tetramethylenedithiocarbamate (TMDTC) are most often used as reagents while pentane, hexane or benzene are used as extraction solvents. 

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