Nafion-based optical sensor for the determination of selenium in water samples

An optical chemical sensor responsive to selenium (SeO32-) in water samples was developed. Its matrix was nafion membrane suffused with an organic ligand p-amino-p'-methoxydiphenylamine or variamine blue (VB). The method of analysis was flow injection (FI) where in the membrane was fixed in a flow-through demountable measuring cell and connected to a computer-controlled simple spectrophotometer. Variamine blue was previously established to determine amounts of selenium in water and other media by means of a spectrophotometer. The method involved reacting selenite with potassium iodide to generate iodine gas, which reacts with variamine blue to form a colored species. Experimental results showed the optrode to be an effective tool in analyzing the selenium content of water samples particularly for remote or in situ applications. Interference studies proved that the method is free of intervention from tested ions. (C) 2004 Elsevier B.V. All rights reserved.