DETECTION OF VANADIUM BY LASER-EXCITED ATOMIC FLUORESCENCE SPECTROMETRY IN A SIDE-HEATED GRAPHITE-FURNACE

Vanadium has been detected at picogram levels in a side-heated integra ted contact graphite tube furnace (electrothermal atomizer) by laser-e xcited atomic fluorescence spectrometry (ETA-LEAFS). The detection lim it of vanadium by this technique has been improved from the nanogram r egion (1.7 ng) to the picogram region by the use of a side-heated inte grated contact graphite tube furnace together with double resonance ex citation in the visible, followed by detection of fluorescence in the ultraviolet region by a solar-blind photomultiplier, which thus comple tely eliminates the influence of scattered laser light in the system. It was found that the limiting factor for the detection of vanadium wa s contamination from the graphite furnaces. The leakage of vanadium ou t of the graphite material thus limited detection to approximately 1 0 pg. The leakage rate depended only weakly on the number of firings of the tube after an initial decrease during the first 20 firings. The d etection limit for vanadium with ETA-LEAFS that would have been obtain ed without contamination from this non-optimized equipment can be esti mated to be 2-3 picograms.