REDUCTION OF INTERFERENCES BY HYDRIDE-FORMING AND TRANSITION-METALS IN CONTINUOUS-FLOW MERCURY COLD VAPOR GENERATION USING MICELLAR MEDIA

Interference effects arising from the transition metals of Cu, Ni, Cd and Pb and the hydrideforming elements As(III), As(V) and Se(IV) in continuous-flow mercury cold vapour generation AAS were alleviated by generating the Hg cold vapour in micellar media. Several acid/micellar media were tested: interferences by transition metals were minimized by HCI/TTAB (tetradecyltrimethylammonium bromide), using NaBH4 as reducing agent, and interferences by hydride-forming elements were reduced most by citric acid/citrate buffer or NH3/SDSS (sodium dioctylsulphosuccinate). A possible mechanism is discussed that involves the formation by electrostatic attraction of a chemical micro-environment, which extends around the Hg2+ or interferent ions. and is dependent on the charge of the ionic surfactants.