Solvent extraction with ammonium pyrrolidinedithiocarbamate and 2,6-dimethyl-4-heptanone for the determination of trace metals in effluents and natural waters

A method is described for the determination of ten trace metals (V, Cr, Fe, Co, Ni, Cu, Zn, Mo, Cd, Pb) in aqueous samples by simultaneous solvent extraction followed by flame atomic absorption spectrometry. 2,6-DimethyI-4-heptanone is preferred to 4-methyl-2-pentanone as the solvent, and ammonium pyrrolidinedithiocarbamate to sodium diethyl-dithiocarbamate as the extractant except when relatively large amounts of iron are present. Calibration graphs are linear, usually over the range 0–50 μg l^-1. The effects of interfering substances, in particular iron, are shown, and the need for calibration by standard additions is demonstrated. The general need for preoxidation of samples is discussed.