APPLICATION OF CHEMICAL MODIFIED ELECTRODE IN COULOMETRIC TITRATION FOR DETERMINATION OF SOLANESOL

ABSTRACT

The problem of large deviation of determination of solanesol by coulometric titration when using direct titration technique and double Pt electrodes amperometric method indicating the end-point has been resolved. In titration process, solanesol, an electroinactive species, can be adsorbed on the surfaces of Pt electrodes and inhibit electrode reactions of Br⁻ and Br₂. Therefore, when titration reaches the end-point, the detected current will slowly change with time, which can make the repeatability of end-point poor. Atomic force microscopy shows the morphology of the electrode surface of adsorbed solanesol. Application of chemically modified electrodes replaced the bare Pt electrodes to indicate the end-point has been investigated. The results show that the Pt electrode coated with Nafion (or PAn) is an excellent indicator electrode. This electrode has advantages in that the indicating signals are sharp and repeatable at end-point. The precision and accuracy of determination of solanesol are satisfactory.

Keywords:

• Coulometric titration
• Chemical modified electrode
• Determination
• Solanesol

ACKNOWLEDGMENT

We are grateful to the Science and Technology Commission of Henan Province and Education Commission of Henan Province for their support. We are also grateful for the solanesol samples supplied by Zhao Jin, Sun Xinqi, and Wang Chaojie.