Solvent Extraction Spectrophotometric Determination of Vanadium Using Sodium Salt of 2-Mercapto-Pyridine-N-Oxide as a Reagent

A solvent-extraction spectrophotometric technique is proposed as a new method for determination of trace quantities of vanadium. Sodium salt of 2-mercapto-pyridine-N-oxide (thione) forms a complex with vanadium instantaneously. The purple 1:2 complex is formed of pH 2.3, easily extracted in chloroform and shows strong absorbance at 500 nm. The extracted complex is found to obey Beer's law in the concentration range of 0.3-18 mgmL-1 vanadium. The molar absorptivity of vanadium thione complex is 2.63´103 L.mol-1.cm-1 with a detection limit of 0.1 mgmL-1. The proposed method offers the advantage of sensitivity and relative freedom from interferences compared to the existing methods. This method is applied in the determination of vanadium in rutile.