TiO₂‐modified Carbon Paste Electrode as a Sensor for the Assay of Weak Organic Acids/Bases and Complex Matrix Samples

Abstract

The construction, general performance characteristics and analytical application of a titanium dioxide–modified carbon paste electrode sensitive to hydrogen ions, based on incorporation of titanium dioxide in a carbon paste matrix, is described. The proposed electrochemical sensor exhibits a linear response in the pH range from 2 to 10, at 25 °C, with a sub‐Nernstian slope. The value of a slope is in a direct correlation with the electrode composition – the optimum content of a titanium dioxide in carbon paste is 30 %. Titanium dioxide‐modified carbon paste electrode shows fast response time and reproducibility, confirmed by different compounds determination in both, individual and complex material, namely, in synthetic and real samples. Besides, the electrode shows high selectivity in the presence of the alkali and the alkaline earth ions as Na+, K+, Ca2+ or Mg2+. The standard deviation of the investigated acids (acetic, oxalic, 5‐sulfosalicylic, p‐toluensulfonic acid, and amino acid‐glycine) and bases (N,N′‐diphenylguanidine and collidine) is less than 1.3 %. The obtained data are compared with those obtained by using a conventional glass pH‐electrode under the same experimental conditions and indicate a high correlation between them.

Review—A Portable Voltammetric Sensor for Determining Titratable Acidity in Foods and Beverages

“…As an electroanalytical method for determining titratable acidity, potentiometric determinations have been recently proposed, and their methods are coupled with flow injection analysis and automated titration systems and have been shown to be useful for the application to real sample analysis of wine and oils. [23][24][25][26][27][28][29] In contrast, amperometric and/or voltammetric determinations are less commonly used. Since most acids are less active electrochemically, it is hard to measure current signals due to the discharge of acids by conventional voltammetric techniques.…”