Date of Award


Document Type

Union College Only

Degree Name

Bachelor of Science






We are interested in developing optical pH sensors based on the fluorescence of an immobilized fluorophor confined on the end of a bifurcated fiber optic. Such optical pH sensors have several potential advantages: they should be inherently less sensitive to electrical noise than conventional pH electro1es, they require no reference electrode, and they make possible remote measurements. The fluorophors evaluated are bound electrostatically to an ion exchange membrane which is then attached to the common end of a bifurcated fiber optic, The fluorophor is excited through one arm and the fluorescence emission is passed through the other arm of the fiber optic to a photomultiplier tube for detection, Before a potential fluorophor is evaluated with this instrument, the pH dependence of the absorption and fluorescence spectra of the dissolved and bound fluorophor are studied, The parameter measured in the sensor is a ratio measurement of the fluorescence emission of one form of the fluorophor when excited,at two different wavelengths, The use of the ratio measurement offers additional advantages over electrodes, Any given fluorophor is limited to sensing a range of +/-1 pH unit on either side of the pKa, Thus, it is necessary to find fluorophors suitable for various pH ranges.