Non-spectral interference effects in platform-equipped graphite atomisers

A large number of physical and chemical phenomena can give rise to non-spectral interference effects in electrothermal atomisers (ETAs). In this paper the processes leading to disturbances in the analytical response by the presence of a matrix are discussed and categorised depending on the stage at which they appear in the furnace procedure. During sample pre-treatment the element of interest can be lost by the formation of volatile analyte and matrix molecules or by analyte expulsion as a result of violent reactions. The difficulties arising from establishing the mechanism of these losses during the pyrolysis are dealt with. Processes during atomisation, giving rise to a reduction of the apparent atomisation efficiency, such as analyte molecule formation or analyte trapping on condensed matrix particles, are described. The discussion is extended to cover related matrix-induced processes which might give rise to a change in the rate of free analyte removal and hence the analytical response. In this connection the discussion will focus on analyte expulsion, alterations in the rate of diffusion of free atoms and reduced mean atom residence times by incidental convective flows. Attention is also given to matrix-induced changes in the spatial distribution of analyte atoms. Several types of the described interference effects have so far not been studied in detail but it can be assumed that they will have minor effects on the analytical response. (C) 1997 Elsevier Science B.V.