Characterization and adsorption of herbicides: AMPA molecule on Cu surfaces.

J.D. FUHR; G. A. BOCAN; J. ASCOLANI; A. DAZA MILLONE; N. TOGNALLI; M.L. MARTIARENA

San Sebastián

Workshop; Brandt-Ritchie Workshop; 2013

BR-Workshop

The detection of pesticides and their degradation products in soil, water, and air is the first step to analyze their effects on the environment and ecosystems. For this reason the development of detection mechanisms has become a challenge and is currently advancing technological developments of biosensors and nanosensors high precision and low cost able to determine the presence of herbicides in different matrices where they could adsorb[1]. Aminomethylphosphonic acid commonly known as AMPA, the main metabolite of glyphosate in the environment, is widely included in the surface water monitoring program for plant protection products, particularly because it can be determined by the same analytical procedure as glyphosate[2]. Here we present a study of the vibration spectra of these molecules using Surface Enhaced Raman Spectroscopy (SERS) and DFT calculations. From calculation within the VASP code including the Van der Waals correction, we characterized the isolated molecules and their adsorption on different surfaces. Various configurations including partially deprotonization of the molecule is addressed. We compared the calculated vibration spectra with the SERS results for AMPA and glyphosate crystal and for glyphosate adsorbed on Cu UPD. This comparison allow us to determine the fingerprint of both molecules when adsorbed on metal surfaces an important ingredient for the development of nanosensors. [1] Emiliano Cortés, Nicolás G. Tognalli, Alejandro Fainstein, María E. Vela and Roberto C. Salvarezza, Phys. Chem. Chem. Phys., 7469, (2009). [2] G.A. Khoury, T.C. Gehris, L. Tribe, R.M. Torres Sánchez & M. dos Santos Afonso, Appl. Clay Sci. (2010)