Developments in the speciation and determination of alkylmetals (Sn, Pb) using volatilization techniques and chromatography-atomic absorption spectroscopy

The behavior and fate of heavy metals in the environment is related to the reactivity of their chemical species in the water phase. Further, alkylmetals are more toxic than their free ionic counterparts and usually their toxicity and impact on the biota increase with the size of the alkylgroup. However, their low concentrations in the environment (ng to pg/L) require highly sensitive techniques. We have developed several sensitive methods for the speciation and determination of alkyltins and alkylleads from aqueous samples. All are derived from volatilization of alkylmetals, preconcentration by cryogenic trapping on chromatographic packing material, speciation by mild thermal desorption, detection in a quartz heated furnace aligned in the beam of an atomic absorption spectrometer and electronic integration of the signal. This paper summarizes optimizing and limiting conditions from the different methods developed. Environmental application on these techniques on extractions of methyltin compounds from sediments are presented and discussed.