A new sensitive and specific test for vanadium with sulphosalicylic acid

A very sensitive and specific test for vanadium^V is described using sulphosalicylic acid as reagent. When this reagent is brought into contact with solid vanadium^V (a drop of the test solution evaporated to dryness on a watch glass) in the presence of concentrated sulphuric acid or 80% syrupy phosphoric acid, a blue colour is developed. Using this colour reaction, it is possible to detect 0.05 μg of vanadium^V in 0.05 ml of test solution. Aluminium^III, arsenic^V, beryllium^II, cadmium^II, chromium^III, chromium^VI, copper^II, iron^III, molybdenum^VI, nickel^VI, tungsten^VI, uranium^VI and vanadium^IV do not interfere with this colour test, although some of them are known to form coloured complexes with sulphosalicylic acid under different conditions. Reducing agents like iron^II, uranium^IV, molybdenum^V and hydroquinone discharge the colour. The colour of the vanadium^V-sulphosalicylic acid compound is also discharged if the temperature is raised to 60°, though it reappears on cooling.