A polymer membrane electrode based on a zinc(II) schiff base complex for the selective determination of sodium benzoate

摘要

A novel poly (vinyl chloride) (PVC) membrane electrode sensitive to benzoate ions was developed. In this electrode, N,N′-bis(salicylidene)-1,2-diaminoethane zinc(II) (Zn(SDE)) complex served as the neutral carrier and o-nitrophenylocthyl ether (o-NPOE) as the plasticizer. We investigated the influences of the neutral carrier, the plasticizer and the composition of the PVC membrane on the potential responses of the electrode. The best response performance was achieved with the following composition (w/w) of the membrane: Zn(SDE): PVC: o-NPOE=2.7: 32.6: 64.7. The electrode showed a sub-Nernstian response with a slope of -51.9mV decade~(-1) in the concentrations range from 2.7 × 10~(-4) M to 1.0 10 × ~(-1) M at pH 4.4. The electrode showed a better selectivity for benzoate ions than other anions such as ClO_(-4), NO_(-3) and Cl~(-1). The obtained mean recovery and standard deviation were 99.5% and 2.4% (n=4), respectively. The content of sodium benzoate was successfully measured in a Zhacai sample, and benzoyl peroxide could also be analyzed through the hydrolysis-potentiometric method in a benzoyl peroxide sample.