Design, operation and analytical characteristics of the filter furnace, a new atomizer for electrothermal atomic absorption spectrometry

The design of a filter furnace (FF), a new atomizer for electrothermal atomic absorption spectrometry (ETAAS) introduced earlier, has been optimized for applications in conventional analytical instrumentation. The factors controlling the analytical characteristics of the FF, i.e. the general geometry of the FF, the configuration of the dosing hole, pyrocoating, the spatial distribution of the shield gas around the FF, the amount of thread, and the porosity of the filter graphite are examined. The analytical characteristics of the improved design of the FF have been investigated and compared with those of tube and platform furnaces. The determination of high- and medium-volatility elements is evaluated in the presence of an excess of volatile matrix. The new FF has a number of advantages: the potential to set the sampling volume in the range 10-100 mu l while maintaining short drying times for any volume; sensitivity levels comparable with those attainable by the stabilized temperature platform furnace (STPF) technique, without the use of matrix modifier; and significant reductions in background and chemical interference. The speed and accuracy of the method is shown in the determination of various elements in the presence of halides, seawater, nitric acid, whole blood and other chemicals. The main disadvantage of the method is that the FF components are destroyed at the temperatures required for the determination of low-volatility and carbide-forming elements.