Adsorption and Displacement of Melamine at the Ag/Electrolyte Interface Probed by Surface-Enhanced Raman Microprobe Spectroscopy

TLDR: In this paper, surface-enhanced Raman spectroscopy (SERS) is evaluated as a quantitative analytical tool for low concentrations of melamine and melamine derivatives in solution, and the results of multiple measurements using a hard cathodic cleaning step in between each adsorption experiment gave a relative standard deviation of 15%.

Abstract: Surface-enhanced Raman spectroscopy (SERS) is evaluated as a quantitative analytical tool for low concentrations of melamine and melamine derivatives in solution. Substantial variations in absolute and relative intensities of SERS bands were encountered using silver sols, which cannot be controlled. Alternatively, it was shown that SERS using a roughened silver electrode, while conditioning the applied potential, permits the acquisition of Raman spectra from electrode spots down to 1 μm in size, and the results of multiple measurements using a hard cathodic cleaning step in between each adsorption experiment gave a relative standard deviation of 15%. The high enhancement factor of the electrode micro-Raman scattering intensity creates a new trace analytical technique for obtaining high-resolution spectra of melamine from dilute aqueous solution (detection limit ∼ 10-7 mol L-1) in the opto-electrochemical cell. As an alternative for the hard cathodic cleaning step, we demonstrated that the cationic surfact...