Comparison of different pre-concentration methods for the determination of trace levels of arsenic, cadmium, copper, mercury, lead and selenium

Abstract

Three methods have been considered for trace metal concentration: (a) liquid-liquid extraction using either ammonium pyrrolidinedithiocarbamate or 8-hydroxyquinoline-5-sulphonic acid; (b) the use of a synthetic poly(dithiocarbamate) resin; and (c) reductive precipitation with NaBH₄. The suitability of method (a) for the determination of metal ions in samples with a complex matrix and high salinity has been investigated. Method (b) was especially useful for speciation studies of trace levels of As^III, As^V, Se^IV and Se^VI. Method (c) gave 1000-fold pre-concentration factors with total recoveries.