Ion-selective electrodes in organic analysis-determination of vanillin by a vanillate-selective electrode

A PVC membrane vanillate-selective electrode has been developed for the indirect determination of vanillin. The vanillate electrode exhibits a Nernstian response in the range 10^-1 ×10^-3 M vanillate with a slope of 59 mV per concentration decade. The electrode has a reasonably wide working pH range (7.5-10.2), a fast response time (less than 30 s) and is stable for at least a month. For the determination of vanillin, vanillin was first oxidised in situ to vanillic acid, which was then determined by the vanillate-selective electrode. The results obtained with the electrode method agree well with those determined by UV spectroscopy. This methodology could be extended to the determination of other aldehydes.