POLYMER-COATED QCR SENSORS FOR THE DETECTION OF ORGANIC-SOLVENTS IN WATER

Poly(ethyl acrylate) (PEA), poly(epichlorohydrin) (PECH) and a silicon -based copolymer of trimethoxypropylsilane/octadecyltrimethoxysilane ( TMPS/ODTMS) were used as sensitive materials for the detection of orga nic solvent molecules in water. Quartz crystal resonators (QCR) with m odified electrode configurations are used to monitor the changes in ma ss and in electrical properties by measuring the shifts in series reso nance frequency (f(s)), parallel resonance frequency (f(p)), and frequ ency of maximum admittance (f(m)), respectively. The result is a multi -information chemical sensor. The sensor signals are completely revers ible at room temperature with the response and recovery time in the or der of minutes under our measurement conditions. The sensitivities obt ained from the measurements of f(m) for all organic solvents investiga ted are generally larger than those obtained from f(s) and f(p). It is also found that there is no correlation between the measured sensitiv ities of the series resonance frequency and the boiling point temperat ures of the organic solvents investigated in the liquid phase under ou r experimental conditions, as is generally obtained in the gas phase.