Molybdovanadic Reagent

In a 150 mL beaker, mix 4 g of finely powdered ammonium molybdate and 0.1 g of finely powdered ammonium vanadate. Add 70mL of water and grind the particles using a glass rod. A clear solution is obtained within a few minutes. Add 20 mL of nitric acid and dilute to 100 mL with water.