DETERMINATION OF IONIC ALKYLLEAD COMPOUNDS IN NATURAL-WATERS BY DIFFERENTIAL-PULSE ANODIC-STRIPPING VOLTAMMETRY

A method for the determination of ionic alkyllead compounds in natural waters is described. The method is based on the extraction of organolead compounds in the form of diethyldithiocarbamate complexes into hexane, their re-extraction with dilute nitric acid (pH 1.5), purification of the aqueous acidic solution from interfering co-extracted dithiocarbamate and determination of alkyllead species by differential-pulse anodic stripping voltammetry. The interference of inorganic lead is prevented by coprecipitation of lead ions with barium sulphate. Distributions of trialkyllead species in a water sample under conditions for extraction were calculated from measured stability constants Of trialkyllead diethyldithiocarbamates and compared with experimental results. With 2.5 1 of water the detection limits for di- and trialkyllead species are ca. 0.5 ng Pb l-1.