Abstract
An ethanol sensor using two chloride ion-selective polymeric membrane electrodes (Cl-ISEs) was developed. Two different polymeric membranes were used, one with o-nitro-phenyloctyl ether (NPOE) and the other with n-decylalcohol (DA) as the plasticizer. The electrical potential of the Cl-ISE fell linearly with increasing ethanol concentration at a given concentration of Cl-. The electrical potential equation is viewed as a function of the concentration of ethanol and Cl-. The responses to ethanol and Cl- differed between plasticizers. The two Cl-ISEs showed nearly Nernstean slopes for Cl- in ethanol solution (0-20%). In addition, each electrode had good linearity for ethanol with a slope of −2.51 mV/ethanol % (NPOE) and −1.01 mV/ethanol% (DA), respectively. The concentration of ethanol and Cl- can be estimated by solving the simultaneous equations derived from the electrical potentials of the two different Cl-ISEs. To decrease the interference from co-existing components, KCl solution was added to the sample until the total concentration was 30 mM. The ethanol sensor using the two Cl-ISEs showed good accuracy in the measurement of ethanol in sake and shochu.
