Determination of nicotinamide in a multivitamin complex by electrochemical-surface enhanced Raman spectroscopy

Abstract

Time resolved Raman spectroelectrochemistry is a powerful technique to prepare useful Surface Enhanced Raman Scattering (SERS) substrates suitable for quantitative analysis. Moreover, following the evolution of the Raman signal with the applied potential the selection of the best conditions for the analysis is quite simple. In this work, gold SERS substrates are prepared on screen-printed electrodes for the determination of nicotinamide, vitamin B3, in a multivitamin complex. The formation of the substrate has been monitored using UV/Vis absorption spectroelectrochemistry and scanning electron microscopy, which confirmed the generation of gold nanoparticles on the electrode surface. This new method has demonstrated to be suitable for the direct quantification of simple test samples using small sample volumes (50 μL). However, it failed when a complex sample, containing several interfering species, was analysed. A high interference on the preparation of the SERS substrate is observed during the analysis of a multivitamin complex. Despite that, nicotinamide was selectively determined in a multivitamin complex using the method of the standard addition, obtaining remarkable figures of merit (R2 = 0.99, %RSD < 9%).