Adaptation of the filter furnace atomizer for atomic absorption determination of less volatile metals

Abstract

The filter furnace atomizer (FF), which has already been proposed for electrothermal atomic absorption spectrometry, provides enhanced sensitivity, a reduction of interferences and reduced analytical time. The main disadvantage of the FF is the rapid destruction of the filter at the atomization temperatures of less volatile or carbide-forming elements. In the current work, radiative heat exchange between the components of the FF was considered to be predominant at high temperature. The thermal behaviour of the FF was therefore examined at fast heating rate as a function of its configuration, the type of graphite used for the components, and the voltage applied. The optimal combination of electrical resistivity, relative dimensions and mass of the FF components was determined for the HGA-500 atomizer. The improvements resulted in a significantly increased lifetime of the FF in the multiple determination of Al, As, Co, Cr, Cu and Ni. The filter withstood 150 firings at 2600°C (hold time 15 s) in the determination of Cr. The theoretical approach can be applied to different types of atomizers.