Sustainable derivatization-free sub-nanoscale spectrofluorimetric environmental assay of fenoxaprop-p-ethyl herbicide in water and soil samples

Fenoxaprop-P-ethyl (FEN) is an aryloxy phenoxy propionate herbicide extensively used in paddy fields. It also risks human health, aquatic organisms, and environmental safety. Hence, there is a crucial need to develop and validate a spectrofluorimetric method that is derivatization-free, chemical-free, cost-effective, easily reproducible, environmentally sustainable, and highly sensitive. In this study, the fluorescence properties of FEN and numerous factors affecting it, such as solvent, pH, and surfactant effects, were carefully studied. The fluorescence intensity of FEN shows excellent linearity over a range of 0.10-10.0 ng/mL at 320 nm upon excitation at 260 nm with an ultra-sensitivity unprecedented in the literature down to 0.03 ng/mL (30 part per trillion, ppt). Therefore, the proposed method has great application potential in effectively monitoring FEN in sewage, river, and soil samples, exhibiting good recoveries (92.0-104.0%) with low relative standard deviations (0.27-6.02%). The high greenness and blueness degree of the designed study was confirmed over other reported techniques regarding FEN detection via the application of AGREE and BAGI tools. The sustainability of the method arises from the utility of the discovered fluorescence properties of FEN and measuring its fluorescence intensity after simple dilution with water without the need for derivatization or any sensitizing chemicals. The proposed method will help with the environmental control of FEN herbicide in water and soil.