THEORETICAL AND PRACTICAL RESPONSE EVALUATION OF A FIBER OPTIC SENSOR FOR CHLORINATED HYDROCARBONS IN WATER

The response behavior of a polymer-coated mid-infrared fiber optical sensor for chlorinated hydrocarbons in water is evaluated practically and theoretically. The sensor response to the target analytes tri- and tetrachloroethylene obtained in a muddy waste water sample is shown to be unaffected by other trace organic pollutants. A theoretical model is presented which can be used to predict the respone of this sensing device. The use of this model allows to simulate the sensor response not only for increasing chlorinated hydrocarbon concentrations, but rather for any change in its concentration in the surrounding medium. In addition, the asymmetric sensor response, depending on the direction of the concentration change and the lag time after a concentration change can be explained by digital simulations and are shown to occur due to diffusion processes in the membrane.