A comparison study of adsorptive transfer voltammetry and solution phase voltammetry for the determination of caffeic acid

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This study reports a comparison of adsorptive transfer and solution phase voltammetric methods for the study of caffeic acid. For this purpose, a platform was prepared by the modification of glassy carbon electrodes (GCEs) with MWCNTs and samarium nanoparticles (SmNPs) by means of an ultrasonic bath. The surface morphology of the platform was characterized using SEM, EDX and XRD. The adsorptive transfer voltammetric method was based on the adsorption of caffeic acid (CFA) at the surface of the modified electrode by keeping it into a solution of CFA. Afterwards, the modified electrode was transferred with the adsorbed species in a cell containing only 0.1 mol L−1 phosphate buffer solution (PBS) for the analysis. The current response of CFA was found to be linear over a concentration from 5.0 × 10−10 mol L−1 to 1.0 × 10−7 mol L−1. The values of the limit of detection (LOD) and limit of quantification (LOQ) were 2.0 × 10−10 mol L−1 and 6.67 × 10−10 mol L−1, respectively. The adsorptive transfer method using the modified electrode (SmNPs/MWCNTs/GCE) has successfully been applied to food samples for determining CFA. The solution phase voltammetry was carried out by dipping the electrode into a voltammetric cell containing CFA. The plot of peak currents was linear over the concentration range of 5.0 × 10−9 mol L−1 –8.0 × 10−8 mol L−1. The values of LOD and LOQ were 2.0 × 10−9 mol L−1 and 6.67 × 10−9 mol L−1 for CFA using a classical solution phase voltammetry at the proposed platform. It was shown that the LOD obtained at adsorptive transfer voltammetry was 10-fold lower when compared to classical solution phase voltammetry.