Premium
Degradation of the insecticides thiamethoxam and imidacloprid by zero‐valent metals exposed to ultrasonic irradiation in water medium: electrospray ionization mass spectrometry monitoring
Author(s) -
Lopes Renata P.,
de Urzedo Ana P. F. M.,
Nascentes Clésia C.,
Augusti Rodinei
Publication year - 2008
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3749
Subject(s) - chemistry , thiamethoxam , imidacloprid , electrospray ionization , neonicotinoid , mass spectrometry , tin , degradation (telecommunications) , aqueous solution , irradiation , electrospray , tandem mass spectrometry , ionization , nuclear chemistry , chromatography , ion , analytical chemistry (journal) , pesticide , organic chemistry , computer science , nuclear physics , agronomy , biology , telecommunications , physics
The degradation of thiamethoxam (1) and imidacloprid (2), prototype neonicotinoid insecticides bearing a characteristic N‐NO 2 moiety in their structures, promoted by a number of zero‐valent metals (Fe, Sn, Zn) upon ultrasonic irradiation in acidic aqueous solution (pH 2) was investigated. It was verified that thiamethoxam (1) and imidacloprid (2) are quickly and almost completely consumed under these experimental conditions (degradation >90% after a reaction time of 30 min) and that ultrasonic irradiation strongly enhances the degradation rate for both insecticides, especially when zinc and tin are employed. Based on the results from electrospray ionization mass (and tandem mass) spectrometry in the positive ion mode, degradation routes for both insecticides, comprising an initial NO 2 → NH 2 reduction, were proposed. In addition, products from the dehydrochlorination of imidacloprid were also found to be formed under these conditions. Copyright © 2008 John Wiley & Sons, Ltd.