Detection of vanadium by laser-excited atomic fluorescence spectrometry in a side-heated graphite furnace

Abstract

Vanadium has been detected at picogram levels in a side-heated integrated contact graphite tube furnace (electrothermal atomizer) by laser-excited atomic fluorescence spectrometry (ETA-LEAFS). The detection limit of vanadium by this technique has been improved from the nanogram region (1.7 ng) to the picogram region by the use of a side-heated integrated contact graphite tube furnace together with double resonance excitation in the visible, followed by detection of fluorescence in the ultraviolet region by a solar-blind photomultiplier, which thus completely eliminates the influence of scattered laser light in the system. It was found that the limiting factor for the detection of vanadium was contamination from the graphite furnaces. The leakage of vanadium out of the graphite material thus limited detection to approximately 10 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 detection limit for vanadium with ETA-LEAFS that would have been obtained without contamination from this non-optimized equipment can be estimated to be 2–3 picograms.