Concentration and Spectrophotometric Determination of Molybdenum with Thiocyanate and Rhodamine 6G

Abstract
A method is described for the determination of molybdenum based on reaction with potassium thiocyanate and Rhodamine 6G in 0.55–0.8 mol dm−3 hydrochloric acid medium. The method is sensitive (ε=2.63×105 l mol−1 cm−1) and obeys Beer’s law over the range 0.04–0.24 ppm of molybdenum. Selectivity can be considerably improved by collecting molybdenum on iron (III) hydroxide. In conjunction with the collection procedure, the method is useful to determine as low as 5 ppb of molybdenum present in 100 cm3 of aqueous samples.