TY - JOUR AU - Thiaré, Diène Diégane AU - Diaw, Pape Abdoulaye AU - Mbaye, Olivier Maurice Aly AU - Sarr, Diegane AU - Gaye-Seye, Mame Diabou AU - Ruellan, Steven AU - Giamarchi, Philippe AU - Delattre, François AU - Coly, Atanasse AU - Aaron, Jean-Jacques PY - 2022/12/30 Y2 - 2024/03/28 TI - Photodegradation study of the fenvalerate insecticide by 1H NMR, 13C NMR, and GC-MS and structural elucidation of its transformation products JF - Macedonian Journal of Chemistry and Chemical Engineering JA - Maced. J. Chem. Chem. Eng. VL - 41 IS - 2 SE - Photochemistry DO - 10.20450/mjcce.2022.2571 UR - https://mjcce.org.mk/index.php/MJCCE/article/view/2571 SP - 193–208 AB - <p>The photolysis of fenvalerate, a pyrethroid insecticide, was studied in acetonitrile by <sup>1</sup>H nuclear magnetic resonance (NMR) and <sup>13</sup>C NMR to identify the site of bond cleavage and gas chromatography-mass spectrometry (GC-MS) to establish the chemical structure of fenvalerate photoproducts. Ultraviolet (UV) irradiation of fenvalerate solutions was performed for 18 h with a solar light simulator, and the photolysis reaction obeyed first-order kinetics. Photolysis half-life time (<em>t</em><sub>1/2</sub>) values ranged between 15.25 and 21.63 h (mean photodegradation percentage = 51.7 %) for <sup>1</sup>H NMR and between 4.55 and 8.06 h (mean photodegradation percentage &gt; 80 %) for <sup>13</sup>C NMR. We observed five sites of bond cleavage, namely carbonyl-tertiary carbon, tertiary carbon-tertiary carbon, carbonyl-oxygen, carboxyl-tertiary carbon, and aromatic carbon-tertiary carbon, yielding photoproducts formation. GC-MS was associated with <sup>1</sup>H NMR and <sup>13</sup>C NMR to obtain a complete photodegradation mechanism. Before UV irradiation, two chromatogram peaks were obtained, due to the two fenvalerate isomers. Under irradiation, both peaks decreased, and new peaks appeared, corresponding to photoproduct formation. After a 12- to 13-h irradiation, 99.39 % of fenvalerate was degraded with a mean rate constant of 0.305 h<sup>–1</sup>. The chemical structure of the formed photoproducts was identified, either by using the National Institute of Standards and Technology (NIST) mass spectral database or by interpreting the mass spectra. Finally, a detailed mechanism was proposed for fenvalerate photodegradation.</p> ER -