Plastic membrane ion-selective electrode for the determination of denatonium benzoate (Bitrex).

A poly(vinyl chloride) matrix membrane ion-selective electrode for the determination of the denatonium ion based on the denatonium salt of tetraphenylborate is described. The response characteristics of the electrode for the denatonium ion and for several quaternary ammonium compounds were studied. The potentiometric determination of denatonium benzoate in rapeseed oil in the range 1-10 ppm agreed to within +/-5% of the spiked amounts. The application of the electrode to the titrimetric determination of several quaternary ammonium compounds using sodium tetraphenylborate as the titrant is also described.