Tebuconazole is a widely used fungicide. The formation of by-products on irradiated titanium dioxide as a photocatalyst was evaluated. Several species derived from tebuconazole degradation were identified and characterized by HPLC/MS(n). A pattern of reactions accounting for the observed intermediates is proposed. Different parallel pathways are operating (and through these pathways the transformation of the molecule proceeds), leading to a wide range of intermediate compounds. All these molecules are more hydrophylic than tebuconazole. The main steps involved are (1) the hydroxylation of the molecule with the formation of three species having [M + H](+) 324; the hydroxylation occurs on the C-1 carbon and on the aromatic ring in the two ortho-positions; (2) the cleavage of a C--C bond with the release of the tert-butyl moiety and the formation of a species having m/z 250; analogously to step 1, also on this species a further hydroxylation reaction occurs; (3) through the loss of the triazole moiety with the formation of a structure with m/z 257.
This article will deal with methods for analyzing residues of pesticides and mycotoxins from molds in food. A general description of each topic is given directing the reader towards some key reviews, books or manuals published in the field with specific references added for more recent papers or topics of particular interest; techniques such as chromatography, spectrophotometry and immunochemical methods have been reviewed. In the first section sampling procedures are discussed, in the second section an overall description of the analytical methods used for pesticide residues in food is given with particular attention to multiresidue methods, in general those used most for assessing residue levels in crops at the international level, with consideration given to those less used methods dedicated to specific compound classes not covered elsewhere. The third section deals with mycotoxins with a brief description of the various mycotoxin types and some properties, followed by some discussion of analytical methods. The description of analytical techniques has been divided into extraction, cleanup and instrumental determination techniques for both pesticides and mycotoxins. Some tables of experimental data are also given.
The last section (four) deals with quality assurance aspects outlining the necessary steps, included interlaboratory trials, needed to validate a method and to assure reliability of the data.
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