Graphite Furnace Modification for Second Surface Atomization

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Abstract
Preliminary results from a simple furnace modification are presented. A graphite condensation site has been located inside a commercial graphite furnace atomizer. Solution samples are deposited on the furnace wall and the analyte and other condensible species “distilled” to this site during a high temperature ash. During the atomization cycle, the analyte is revaporized from the “plug” into the higher temperature furnace environment. The plug is radiatively heated and can lag behind the wall temperature by more than 1000 K, thus providing atomization into a higher temperature environment which is more nearly isothermal. The heating program with analyte transfer permits extremely high ash temperatures to be used and offers the possibility of separating the analyte from gaseous, thermal decomposition products from the matrix. Additionally, distortions of the analytical absorbance signal caused by degradation in the pyrolytic surface of the furnace are minimized when atomization from the secondary surface is employed. Limits of detection for Ag, Cr, Cu, Fe, Pb, Sn, and Zn are within a factor of 2 of values determined using wall atomization. Studies are presented on the interference of sulfate on Sn analysis. Improved peak height sensitivity and a decreased dependency on sulfate concentrations have been observed.