Sodium cobaltinitrite is inorganic compound with the formula Na3Co(NO2)6. The anion of this yellow-coloured salt consists of the transition metal nitrite complex [Co(NO2)6]3-. It was a reagent for the qualitative test for potassium and ammonium ions.

Although the sodium cobaltinitrite is soluble in water, it forms the basis of a quantitative determination of potassium, thallium, and ammonium ions. Under the recommended reaction conditions the insoluble double salt, K2Na[Co(NO2)6]·H2O is precipitated and weighed.

1.583 g of potassium chloride in water, and dilute with water to 500 mL. To 10.0 mL of this solution (20 mg of K2O) in a 50 mL beaker, add 2 mL of 1 N nitric acid and 8 mL of water. Dissolve 5 g of the sodium cobaltinitrite in water, dilute with water to 25 mL, and filter.

SODIUM COBALTINITRITE AR