Development of a fiber-optic chemical sensor for multicontaminant monitoring of environmental systems

Abstract

There are many instances where information regarding chemical concentrations of inaccessible regions may be desired. For example, in situ and real-time monitoring of groundwater systems would improve knowledge of the fate and flow of contaminants. In response to this need, a fiber-optic chemical sensor has been developed that incorporates an immobilized fluorescent indicator. The indicator, PRODAN, is found to fluoresce at varying wavelengths for an array of anthropogenic organics. A polyacrylamide is utilized to bind the PRODAN chemically to the optical fiber to develop a long-term in-line chemical probe. The probe is applied using a high-powered light source for excitation in the ultraviolet range. Experimental results are given for pure organic solvents: acetone, cyclohexane, chloroform, toluene, and cyclohexane. the results of the optical-fiber tests are compared to a prior direct fluorescence study. In order to determine the intensity response curve for decreasing concentrations of organic chemicals, a parametric study has been performed. After full development and optimization, the remote identification and tracking of organics could greatly increase knowledge of the fate and flow of contaminants in many environmental systems.