DOPED SOL-GEL FILMS FOR THE DEVELOPMENT OF OPTOCHEMICAL ETHANOL SENSORS

Porous glass films with immobilized solvatochromic dyes were investiga ted to develop an optochemical sensor for the determination of ethanol in water. Depending on the polarity of a solvent, i.e. content of eth anol in water, the immobilized indicators changed their fluorescence p roperties. Sensing films were prepared by immobilizing the dye with a sol-gel process. After preconditioning, these films were usable over a period of 5 weeks under continuous operation. The detection limit of ethanol in water was 0.6 vol.%, the response being linear in the range 0-50 vol.% ethanol. The response time was less than 5 min and the int eraction with ethanol was reversible. The effect of pH and the tempera ture of the sample on the sensor properties were investigated.