Abstract
A total-internal-reflection-type fiber-optic sensor having a crosslinked Chitosan/poly(vinyl alcohol) blended membrane as the cladding responded reversibly to organic solvents such as alcohols, acetone, acetonitrile, dioxane and chloroform in water. The response was explained on the basis of an increase in the refractive index of the cladding membrane by organic solvents. Larger responses were observed to solvents having lower dielectric constants. When the cladding membrane was coated with a thin Teflon protective membrane, the response time depended on the vapor pressure of the solvents, and was 30s for acetone with a high vapor pressure. The response to chloroform was ca. ten-times larger than that to ethanol, and a linear relationship was obtained in the concentration range of 5 to 50mM.
