Spectrophotometric determination of vanadium using rhodamine-B

A new reagent system using rhodamine-B dye for the determination of vanadium is described. The method is based on the reaction of vanadium with acidified potassium iodide to liberate iodine. The liberated iodine bleaches the pink colour of rhodamine-B, which is measured at 553 nm. Beer's law is obeyed over the concentration range of 2-16 mu g of vanadium in final solution volume of 25 ml (0.08-0.64 ppm). The apparent molar absorptivity and Sandell's sensitivity were found to be 1.3 x 10(5) L mo(-1) cm(-1) and 0.0009 mu g cm(-2) respectively. The method is simple, sensitive and satisfactorily applied to ppm level for the determination of vanadium in different environmental and biological samples.