Document Detail

Identification of pesticide transformation products in food by liquid chromatography/time-of-flight mass spectrometry via "fragmentation-degradation" relationships.
MedLine Citation:
PMID:  17194155     Owner:  NLM     Status:  MEDLINE    
The identification of transformation products of pesticides in foodstuffs is a crucial task difficult to tackle, due to the lack of standards and scarce information available. In this work, we describe a methodology for the identification and structural elucidation of pesticide transformation products in food. The proposed strategy is based on the use of liquid chromatography electrospray time-of-flight mass spectrometry (LC/TOFMS): accurate mass measurements of (molecule and fragment) ions of interest are used in order to establish relationships between fragmentation of the parent pesticides in the instrument (in-source CID fragmentation) and possible degradation products of these pesticides in food. Examples of this strategy showing the potential of LC/TOFMS to determine unknown pesticides in food are described in two different real samples, suggesting that pesticides often are transformed into degradation products in the same fashion that they are fragmented in the instrument. Using the proposed approach and without using standards a priori, based solely on accurate mass measurements of ions and "fragmentation-degradation" relationships, we have identified two parent pesticides (amitraz and malathion) along with six degradation products, m/z 253 (N,N'-bisdimethylphenylformamidine), 163 (N-2,4-dimethylphenyl-N-methyl formamidine), 150 (2,4-dimethylformamidine), and 122 (2,4-dimethylaniline) from amitraz, and m/z 317 and 303, due to ether hydrolysis of methyl and ethyl groups from malathion. Structures for these species were proposed, and the potential of the proposed approach was critically discussed.
Juan F García-Reyes; Antonio Molina-Díaz; Amadeo R Fernandez-Alba
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Analytical chemistry     Volume:  79     ISSN:  0003-2700     ISO Abbreviation:  Anal. Chem.     Publication Date:  2007 Jan 
Date Detail:
Created Date:  2006-12-29     Completed Date:  2007-03-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  307-21     Citation Subset:  IM    
Department of Physical and Analytical Chemistry, University of Jaén, 23071 Jaén, Spain.
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MeSH Terms
Amidines / analysis,  chemistry
Aniline Compounds / analysis,  chemistry
Chromatography, Liquid / methods*
Food Analysis*
Food Contamination / analysis*
Malathion / analysis,  chemistry
Mass Spectrometry / methods*
Pesticide Residues / analysis*,  chemistry
Time Factors
Toluidines / analysis,  chemistry
Reg. No./Substance:
0/Amidines; 0/Aniline Compounds; 0/Pesticide Residues; 0/Toluidines; 121-75-5/Malathion; 33089-61-1/amitraz; 95-68-1/2,4-xylidine

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