Determination of Chromium in Vanadium Alloys by Flame Atomic Absorption Spectrometry

FAAS was applied to the determination of Cr in a vanadium based alloy, a ternary componental alloy of V, Cr and Ti. 0.100 0 g of the alloy sample was taken and dissolved in 5 mL of H₂SO₄ (1+1) and 2 mL of HNO₃ by heating, then evaporated to fumes of sulfuric acid. After cooling, the solution was diluted to 100.0 mL with water in a volumetric flask. An aliquot containing chromium approximately in the range of 0.1-0.5 mg was taken and transferred to a 100 mL volumetric flask, and its volume was made up to 100.0 mL with water after adding 10 mL of 20 g·L^-1 K₂SO₄ solution, which was added as an anti-interfering reagent to overcome the interferences from the coexisting V and Ti ions as well as a sensitizing reagent to raise the signal intensity. Chromium content of the sample solution was then determined by FAAS. Under the optimum condition, linear relationship between values of absorbancy and the corresponding mass concentration of Cr was obtained in the range of 1.00-5.00 mg·L^-1. A substantial V based alloy was analyzed by the proposed method, and value of RSD (n=6) found for chromium was 0.64%. Using V-Cr-Ti alloy as matrix, recovery was tested by adding chromium standard solution at 2 concentration levels, average value of recovery found was 97.1%.