A Simple Sensitive Spectrophotometric Method for the Determination of Ce⁴⁺ Using Variamine Blue as a Chromogenic Reagent

Abstract.

A rapid and sensitive spectrophotometric method is described for the determination of trace amounts of cerium using Variamine Blue (VB) as a chromogenic reagent. The proposed method is based on the reaction of cerium with potassium iodide in acidic medium to liberate iodine, which oxidizes Variamine Blue to give a violet colored species with an absorption maximum at 560 nm. Beer’s law was obeyed in the range 2–10 µg mL⁻¹ of cerium. The molar absorptivity and Sandell’s sensitivity are found to be 1.65×10⁴ L mol⁻¹ cm⁻¹ and 8.48×10⁻³ µg cm⁻², respectively. The proposed method has been successfully applied to the determination of cerium in alloy and synthetic mixtures.