Measurement of the ethanol concentration in a sake using liquid membrane ion-selective electrode containing potassium tetrakis (4-chlorophenyl)

An ion sensor with plasticized poly (vinyl chloride) membrane containing potassium tetrakis (4-chlorophenyl) borate was developed for measuring of concentration of ethanol in sake as a non-distilled liquor including high concentration of ion matrixes. The effect of ions that were included in the sake on the potential response was investigated. The co-existence of cations, such as organic amines, strongly interfered with the potential response, though anions didnot. The addition of KCI was effective in reducing the interference of cations. However, the reductive effect was insufficient for measuring of ethanol concentration in sake. Therefore sake was treated with a mixed cation and anion exchange resin before the measurement. The ion sensor measurement established with the ion-exchange pretreatment provided a quantitative result, such that the measured concentration agrees with the concentration obtained by gas chromatography within 1%.