Surfactant assisted chemical vapour generation of silver for AAS and ICP-OES: a mechanistic study

Abstract

A chemical vapour generation (CVG) procedure for the production of volatile species of Ag was developed and studied using AAS and ICP-OES detection. A characteristic mass of 0.12 ng was achieved using a miniature diffusion flame atomizer-AAS system, whereas a 38-fold higher sensitivity (as cps per ng of introduced analyte) compared with conventional liquid nebulization was obtained with ICP-OES. The overall efficiency of introduction of Ag to the plasma was verified to be over 20%. More than one order of magnitude enhancement of efficiency was obtained by the addition of a surfactant (Triton X-100 in combination with an antifoaming agent), the effect of which, however, cannot be ascribed to the formation of organized media. Experiments concerning the mechanism of the CVG, transport and memory effect are discussed: Ag CVG is not a simple one-step process as is the case for CVG of selenium, but rather a two-step procedure. Transport properties of the volatile Ag species resemble more the transport of the liquid aerosol than a simple gaseous species such as H₂Se. Possible alternatives concerning the identity of the volatile metal species are presented.