Liquid-liquid, discontinuous, counter-current solvent extraction for determination of trace constituents in geological materials—II : Extraction with solvents heavier than water

Abstract

A new analytical technique has been developed for the determination of trace elements in sea water and other natural waters. The method consists of the use of liquid-liquid, counter-current, solvent extraction with solvents heavier than water. Relatively large volumes of sea water form the moving aqueous layer in the extraction procedure, whereas the lower stationary layer comprises the chelating agents dithizone or 8-hydroxyquinoline dissolved in carbon tetrachloride and chloroform, respectively. Elements are progressively absorbed from the sea water as the aqueous layer passes along the extraction train. Trial experiments with sea water containing additives shows that solutions of 8-hydroxyquinoline and to a lesser extent dithizone are capable of quantitatively retaining a number or elements in a small number of extraction tubes. An experiment has been carried out with a sample of pure sea water from which Mn, Pb, Mo, Sn, Ni, Al, V, Ag, Zn and La were quantitatively extracted into a solution of 8-hydroxyquinoline in chloroform; the elements were all determined spectrographically. It is considered that the method should have wide applications in the analysis of trace elements in sea water because enrichment factors of 400,000 are obtained for the concentrations of these elements. The technique is simple and comparatively free from contamination dangers.