Effect of Atomization Surface on the Quantitation of Vanadium by Electrothermal Atomization Atomic Absorption Spectrometry

Abstract

The effect of four different atomization surfaces (uncoated graphite, pyrolitically coated graphite, continuously in situ coated graphite, and molybdenum coated graphite) on the quantitation of vanadium by electrothermal atomization atomic absorption spectrometry was investigated. For the four different surfaces, tube lifetimes ranged from a high of 410 firings (uncoated graphite) to a low of 230 firings (molybdenum coated graphite), mass changes in the range from 5.6 to 7.2% were found, and the peak shape from the uncoated and pyrolytically graphite surface approached a good degree of symmetry. The single addition of several matrix modifiers to an uncoated graphite surface affected the signal over a range of −106.5% for ammonium molybdate to +12.3% for magnesium nitrate. A combined matrix modifier improved the signal from all four surfaces in the range from 12.8 to 34.0%. Detection limits ranged from 2 μg/L for the pyrolytic surface to 19 μg/L for the molybdenum coated surface. Electron micrographs of the four surfaces at various stages of the tube lifetime showed the deterioration of the surface with increasing use.