Miniature High Temperature Laminar Diffusion Flames for Analytical Atomic Spectrometry

Abstract

Miniature high temperature laminar diffusion flames are described for analytical atomic spectrometry. Fuel flow rates below 0.2 liters/min are used and temperatures in excess of 2500 K are maintained in a stable, fuel-rich combustion environment of low background emission. The internal atomizer chamber volume is 1.5 ml (below the burner top). A graphite cup atomizer is used for sample introduction and is “fired” inside the miniature burner head in the presence of “fuel only.” Oxidant diffuses into the fuel zone above the burner top. Compared to conventional electrothermal atomizers, the miniature N₂O → H₂ diffusion flame greatly reduced particulate light scattering in continuum excited atomic fluorescence spectrometry. In atomic absorption spectrometry, the hot miniature flame serves to effectively reduce the molecular spectral interference due to gaseous diatomic alkali halides. The enhanced gas phase concentration of atomic products presently results in a concentration sensitivity improvement of 30 times over conventional premixed flames used in Eimac continuum excited atomic fluorescence. The improvement in absolute weight sensitivity is 140 times for atomic fluorescence.