Abstract
AbstractThe photoinduced degradation of the insecticide imidacloprid in natural water samples was performed in order to describe its abiotic degradation. Numerous degradation products could be identified with the help of spectroscopic methods. The main photoproducts were 1‐[(6‐chloro‐3‐pyridinyl)methyl]‐N‐nitroso‐2‐imidazolidinimine, 1‐[(6‐chloro‐3‐pyridinyl)methyl]‐2‐imidazolidinimine (which is known to be more toxic for warm‐blooded animals than imidacloprid) and 1‐[(6‐chloro‐3‐pyridinyl)methyl]‐2‐imidazolidinone. Besides numerous other degradation products, 6‐chloro‐nicotine‐amide was identified as the end product of the photolytic reaction. The photoinduced reaction of imidacloprid followed pseudo first‐order reaction kinetics and resulted from a triplet‐controlled intermediate state with a triplet energy between 281–290 kJ/mol and an half‐life time of 4.6×10–9 s. With the help of measured quantum yields (ΦS), the half‐life time of imidacloprid in natural waters was estimated at 3 days. The calculated half‐life times of 1‐[(6‐chloro‐3‐pyridinyl)methyl]‐2‐imidazolidinimine was much shorter, 0.24 days, while those of 1‐[(6‐chloro‐3‐pyridinyl)methyl]‐2‐imidazolidinone and 6‐chloro‐nicotine‐amide were higher at 270 and 660 days, respectively.
Published Version
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