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 co ntinuous-flow mercury cold vapour generation AAS were alleviated by ge nerating the Hg cold vapour in micellar media. Several acid/micellar m edia were tested: interferences by transition metals were minimized by HCI/TTAB (tetradecyltrimethylammonium bromide), using NaBH4 as reduci ng agent, and interferences by hydride-forming elements were reduced m ost by citric acid/citrate buffer or NH3/SDSS (sodium dioctylsulphosuc cinate). A possible mechanism is discussed that involves the formation by electrostatic attraction of a chemical micro-environment, which ex tends around the Hg2+ or interferent ions. and is dependent on the cha rge of the ionic surfactants.