Optimalization of Poly(neutral red) Coated-wire Electrode for Determination of Citrate in Soft Drinks

This report presents an optimization of potentiometric measurements withcitrate-selective electropolymerized poly(neutral red) electrodes. The optimal backgroundelectrolyte for these measurements is a TRIS buffer with nitrate at pH 8.5. The electrodesdescribed here exhibit stable and reproducible near-Nernstian response to citrates with alow detection limit of 6 — 10-6 M. Electrodes polymerized from sulfuric acid andacetonitrile are compared in detail. Simple and sensitive method for quantification ofcitrate in real-life samples by potentiometry with poly(neutral red) electrodes arepresented. Data from potentiometric measurements of citrate are compared with capillaryelectrophoresis.