Detection of aromatic hydrocarbons in air and water by using xerogel layers coated on PCS fibers excited by an inclined collimated beam

This paper deals with experimental results on the sensitivity of silica optical fibers coated with detection xerogel membranes to benzene and toluene both in gaseous mixtures and in aqueous solutions. For this purpose thin polysiloxane and methyl-group-doped polysiloxane xerogel membranes are applied on straight segments of PCS fibers. The interaction of these membranes with hydrocarbons is investigated on the basis of changes of the output optical power from the fibers excited by an inclined collimated beam. The results obtained show that the hydrophobic methyl-group-doped xerogel layers exhibit higher sensitivity to hydrocarbons both in the gaseous phase and in solutions. The detection limits are about 230 ppm vol. for toluene in air and about 9 mg/l for toluene in water. Both the membranes show lower sensitivity to benzene than to toluene. (C) 2003 Elsevier B.V. All rights reserved.