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

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 met allic bar with a cavity in it. Absorbance-concentration ratios of orig inal and standardized lignite samples were different. However, upon mi xing with a proper amount of graphite powder, the absorbance-concentra tion 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 hei ght. Therefore, accuracy of V determination is not affected by the pre sence of Al in the sample.