A New Reagent System for Photometric Analysis of Selenium in Complex Materials

Department of Chemistry, Ravishankar University, Raipur-492 010

Manuscript received 22 June 1981, revised 11 December 1981, accepted 28 April 1982

A new reagent system consisting of 4-nitrophenyl hydrazine and 8-quinolinol is described for the photometric determination of selenium. 4-Nitrophenyl hydrazine is oxidised with selenious acid in 6 M hydrochloric acid to 4-nitrophenyl-diazonium chloride which is then coupled with 8-quinolinol to form an 'azoxine' dye. The dye gives intense purple colour in alkaline medium with an absorption maxima at 550 nm. The colour system obeys Beer's law in the range of 7-45 μg Se/25 ml. The molar absorptivity and Sandell's sensitivity are 3.2 x 10⁴ 1. mole^-1 cm^-1 and 0.0025 μg/cm²  respectively. The optimum reaction conditions and other analytical parameters are evaluated. The effect of various ions is discussed. The method is applied for detection and determination of selenium in complex materials such as cabbage leaf and cigarette paper.