Analytical Sciences

Use of the Sulfide Mineral Pyrite as Electrochemical Sensor in Non-aqueous Solutions: Potentiometric Titration of Weak Acids in Acetonitrile, Propionitrile and Benzonitrile

Ljiljana MIHAJLOVIC,* Snezana NIKOLIC-MANDIC,** Branislav VUKANOVIC,*** and Randel MIHAJLOVIC*

*Department of Chemistry, Faculty of Sciences, University of Kragujevac, Radoja Domanovica 12, P. O. Box 60, 34 000 Kragujevac, Serbia
**Faculty of Chemistry, University of Belgrade, Studentski trg 16, 11 000 Belgrade, Serbia
***Technical High School, 37000 Kruševac, Serbia

Natural monocrystalline pyrite as a new indicator electrode for the potentiometric titration of weak acids in acetonitrile, propionitrile and benzonitrile was studied. The investigated electrode showed a linear dynamic response for p-toluenesulfonic acid concentrations in the range from 0.1 to 0.001 M, with a Nernstian slope of 74 mV per decade. Sodium methylate, potassium hydroxide and tetrabutylammonium hydroxide (TBAH) proved to be very suitable titrating agent for this titration. The response time was less than (11 s) and the lifetime of the electrode is long. The advantages of the electrode are log-term stability, fast response, and reproducibility, while the sensor is easy to prepare and of low cost.

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