Electrocatalytic Determination of Hydroquinone with Mn+ Modified Gold-5-amino-2-mercaptobenzimidazole Self-Assembled Monolayer Electrodes

Application of immobilized metal cations on the topside of gold-5-amino-2-mercaptobenzimidazole self-assembled monolayer (Au-5A2MBI-Mn+ SAM, Mn+:Cu2+ or Ag+) for electrocatalytic determination of hydroquinone (H2Q) is described by voltammetric method. Several parameters were investigated to evaluate the performance of the sensors. Calibration curves for H2Q concentrations were linear from 1.0 × 10-5 to 4.0 × 10-4 M (r = 0.998) for Au-5A2MBI, from 1.0 × 10-5 to 6.0 × 10-4 M (r = 0.998) for Au-5A2MBI-Cu2+, and from 2.0 × 10-6 to 2.0 × 10-5 M (r = 0.996) and 1.0 × 10-4 to 1.0 × 10-3 M (r = 0.991) for Au-5A2MBI-Ag+ SAM modified electrode. The respective detection limits were found as 6.5 × 10-6, 4.6 × 10-6 and 1.8 × 10-7 M. Both Cu2+ and Ag+ ions were found to have a good electrocatalytic effect on the oxidation of H2Q; however, Ag+ was a more effective catalyst and showed better sensitivity and lower detection limit than all other tested electrodes. Au-5A2MBI-Ag+ SAM electrode was used as a suitable sensor for determination of H2Q in a radiolysis developing agent as real sample. The results obtained by using proposed sensor and that obtained by an ASTM reference method were in good agreement at the 95% confidence level.