TEMPERATURE PROFILES OF TURBULENT HYDROGEN DIFFUSION FLAMES USED IN ATOMIC FLUORESCENCE SPECTROMETRY

The temperatures of H2/Air, H2/Ar/entrained Air, H2/N2O, and H2/entrained Air flames supported on total-consumption burners have been measured with the aid of an iridium/60% iridium-40% rhodium thermocouple. The flames have been used in atomic fluorescence and atomic emission studies, and results are quoted for flame temperatures measured with and without the aspiration of water. A full discussion of the use of thermocouples in measuring flame temperatures is given together with complete temperature contours and also vertical height profiles for a variety of flames. The principal source of oxidant in all the flames examined was entrained air, the main purpose of the aspirant gas being to create sufficient turbulence. As a result, the enhancement of atomic fluorescence quantum efficiency, obtained by aspiration using argon, is small (co. 10-20%). Generally, easily volatilized and atomized elements can be determined above the visible portion of the flame, whereas other elements must be determined within the flame. For the latter elements, the height at which maximum fluorescence occurs does not necessarily correspond to the most favorable signal-to-noise ratio. © 1969, American Chemical Society. All rights reserved.