Use of multivariate curve resolution analysis in the spectroelectrochemistry of 9,10-anthraquinone reduction in dimethylformamide solution

Abstract

A multivariate curve resolution analysis has been conducted to deconvolute the spectroelectrochemical data of 9,10-anthraquinone (AQ) reduction. The experiments were carried out in dimethylformamide solution containing small amounts of benzoic acid as a proton source at an optically transparent thin layer electrode (OTTLE). Two electrochemical techniques, namely a potential step method and chronoabsorptiometry were employed. In the former, the absorbance spectra of anthraquinone solutions at different applied potentials were recorded, and in the latter technique, a −1.90 V potential was applied to the OTTLE and the absorbance spectra of the solution were recorded at different time intervals. For both techniques, factor analysis revealed that three chemical components coexist in the system, which can be attributed to AQ − , AQH − and AQ 2−. By using a multivariate curve resolution analysis, the concentration profiles and pure spectra of the components were determined. The results of the potential step method revealed that the maximum amount of AQ − is produced at −1.25 V, and application of more negative potentials causes an decreased amount of AQ − at the expense of the evolution of AQH −. Finally, the AQ 2− species is produced at −1.6 V. The chronoabsorptiometric results showed that AQ − is not stable at 1.9 V and rapidly converts to AQ 2−.