DIRECT DETERMINATION OF THE VANADIUM CONTENT OF LIGNITE BY ATOMIC-ABSORPTION SPECTROMETRY USING A GRAPHITE-FURNACE ATOMIZER AND A SOLID SAMPLE

Abstract

The vanadium content of lignite is directly determined using powdered samples and a graphite furnace atomizer. Powdered lignite samples were standardized by the standard addition method and mixed with graphite powders; they were then introduced into the furnace using a simple metallic bar with a cavity in it. Absorbance-concentration ratios of original and standardized lignite samples were different. However, upon mixing with a proper amount of graphite powder, the absorbance-concentration ratio of the lignite samples approached the same limiting value. Spectral interference of Al was observed at 318.4 nm, at which atomic absorption of V is measured. However, since Al is more volatile than V, signals due to Al disappear before signals of V reach their peak height. Therefore, accuracy of V determination is not affected by the presence of Al in the sample.