An easy spectrophotometric determination of selenium using azure B as a chromogenic reagent

Abstract

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of trace amounts of selenium in water samples, soil, plant materials and human hair. The proposed method is based on the reaction of selenium with potassium iodide in acidic medium to liberate iodine. The liberated iodine bleaches the violet colour of azure B, which is measured at 644 nm. This decrease in absorbance is directly proportional to selenium concentration. Beer’s Law was obeyed in the range 2.0-10.0 µgmL^-1 of selenium. The molar absorptivity, Sandell’s sensitivity, quantitation limit and detection limit of the method were found to be 0.9473 <img src='/image/spc_char/cross.gif' border=0> 10⁵ L mol^-1 cm ^-1, 8.33 <img src='/image/spc_char/cross.gif' border=0> 10^-4 µg cm^–2, 0.070 µgmL^-1 and 0.023 µgmL^-1, respectively. The proposed method has been successfully applied to the determination of selenium in various samples.