Application of 2-mercaptobenzothiazole self-assembled monolayer on polycrystalline gold electrode as a nanosensor for determination of Ag(I)

Fabrication and application of a voltammetric sensor based on gold 2-mercaptobenzothiazole self-assembled monolayer (Au-MBT SAM) for determination of silver ion is described. Preliminary experiments were performed to characterize the monolayer. The surface pKa determined for the MBT monolayer is 7.0. This value was obtained by impedimetric titration of the monolayer in the presence of Fe(CN)63−/4− as a redox probe. The extent of surface coverage was evaluated as 1.52 × 10−9 mol cm−2 based on charged consumed for reductive desorption of the monolayer in the 0.50 M NaOH solution. Then the sensor was used for determination of Ag(I) by square wave voltammetry. The parameters affecting the sensor response, such as pH and supporting electrolyte, were optimized. A dynamic calibration curve with two linear parts was obtained in the concentration ranges of 5 × 10−8-8 × 10−7 and 1 × 10−6-1 × 10−5 M of Ag(I). The detection limit adopted from cathodic striping square wave voltammetry was as 1 × 10−8 M for n = 7. Furthermore, the effect of potential interfering ions on the determination of Ag(I) was studied, and an appropriate method was used for the elimination of this effect.