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

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 560nm. Beers law was obeyed in the range 2–10µg mL^–1 of cerium. The molar absorptivity and Sandells sensitivity are found to be 1.65×10⁴L mol^–1cm^–1 and 8.48×10^–3µgcm^–2, respectively. The proposed method has been successfully applied to the determination of cerium in alloy and synthetic mixtures.     

Spectrophotometric Determination of Selenium Using Potassium Iodide and Starch as Reagents

 This study describes a rapid and sensitive spectrophotometric method for the determination of trace amounts of selenium, using starch and iodine as chromogenic reagents. The proposed method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine. This reacts with starch to form a blue colored species with an absorption maximum of 570 nm. Beer’s Law was obeyed in the range of 2–12 μg of selenium. The molar absorptivity and Sandell’s sensitivity were found to be 1.40×10⁴ L mol⁻¹ cm⁻¹ and 5.45×10⁻³ μg cm⁻² respectively. The proposed method was successfully applied to determine selenium in a sample of natural water, polluted water, soil sludge, biological samples and human hair. Correspondence: Department of Studies in Chemistry, Managalore University, Mangalagangothri, Karnataka, India. e-mail: nbadiadka@yahoo.co.uk Received August 2, 2002; accepted October 29, 2002