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Highly Sensitive SERS Detection of Neonicotinoid Pesticides. Complete Raman Spectral Assignment of Clothianidin and Imidacloprid

preprint
revised on 27.03.2020 and posted on 27.03.2020 by Niamh Creedon, Pierre Lovera, Jose Julio Gutierrez Moreno, Michael Nolan, Alan O'Riordan
The use of Surface Enhanced Raman Spectroscopy in the development of low cost, portable sensor devices that can be used in the field for nitroguanidine neonicotinoid insecticide detection is appealing. However, a key challenge to achieving this goal is the lack of detailed analysis and vibrational assignment for the most popular neonicotinoids. To make progress towards this goal, this paper presents an analysis of the bulk Raman and SERS spectra of two neonicotinoids, namely clothianidin and imidacloprid. Combined with first principles simulations, this allowed assignment of all Raman spectral modes for both molecules. To our knowledge, this is the first report of SERS analysis and vibrational assignment of Clothianidin and a comprehensive assignment and analysis is provided for imidacloprid. Silver nanostructured surfaces were fabricated for qualitative SERS analysis, which provides the characteristic spectra of the target molecules, and demonstrates the ability of SERS to sense these molecules at concentrations as low as 1 ng/L. These detection limits are significantly lower than reported solid state electrochemical techniques and are on a par with high-end chromatographic-mass spectroscopy laboratory methods. These SERS sensors thus allow for the selective and sensitive detection of neonicotinoids, and provides complementary qualitative and quantitative data for the molecules. Furthermore, this technique can be adapted to portable devices for remote sensing applications. Further work focuses on integrating our device with an electronics platform for truly portable residue detection.

Funding

Environmental Protection Agency, Grant: 2015-W-MS-21

VistaMilk Centre Science Foundation Ireland, Department of Agriculture Food and the Marine Grant Number 16/RC/3835

Science Foundation Ireland Research Centre Connect (13/RC/2077)

History

Email Address of Submitting Author

michael.nolan@tyndall.ie

Institution

Tyndall National Institute, UCC

Country

Ireland

ORCID For Submitting Author

0000-0002-5224-8580

Declaration of Conflict of Interest

No conflict of interest

Version Notes

Version 2, removing electrochemistry

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