PRECONCENTRATION OF ORGANIC-COMPOUNDS AT A DIPHENYL ETHER GRAPHITE PASTE ELECTRODE AND DETERMINATION OF VANILLIN BY ADSORPTIVE EXTRACTIVE STRIPPING VOLTAMMETRY

A carbon paste electrode containing diphenyl ether (dp-CPE) as a paste liquid was prepared and the preconcentration of various electroactive aromatic compounds at this electrode was studied and compared with the commonly used carbon paste electrode containing Nujol as paste liquid (nu-CPE). All compounds tested showed a much greater tendency for preconcentration at the dp-CPE than the nu-CPE, and many compounds proved to be readily preconcentrated exclusively at the dp-CPE, thus allowing their sensitive determination by adsorptive-extractive stripping voltammetry (typical concentration range 0.6-4-mu-mol dm-3). The selectivity of these determinations was enhanced by applying the 'medium-exchange' procedure. Based on these findings, a simple procedure was developed for the electrochemical determination of vanillin in food samples.