V2O5 98%. 99%. 99.5% 99.7% 99.9% V2O4 2.5 1.0 Si 0.25 0.08 0.05 0.02 0.01 Fe 0.3 0.08 0.01 0.005 0.002 S 0.03 0.01 0.01 0.008 0.005 P 0.05 0.03 0.01 0.008 0.005 As 0.02 0.01 0.01 0.005 0.001 Na2O+K2O 1.5 0.7 0.2 0.1 0.05