Retrospective screening of pesticide metabolites in ambient air using liquid chromatography coupled to high-resolution mass spectrometry

• A retrospective screening has been developed for airborne metabolites of pesticides .
• A customized database of 240 pesticide metabolites was built for suspect analysis.
• 34 pesticide metabolites were identified in ambient air.
• 11 metabolites were confirmed at concentration from 6.78 to 198.31 pg m−3.

A new methodology for the retrospective screening of pesticide metabolites in ambient air was developed, using liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (UHPLC-HRMS), including two systematic workflows (i) post-run target screening (suspect screening) and (ii) non-target screening. An accurate-mass database was built and used for the post-run screening analysis. The database contained 240 pesticide metabolites found in different matrixes such as air, soil, water, plants, animals and humans. For non-target analysis, a “fragmentation-degradation” relationship strategy was selected. The proposed methodology was applied to 31 air samples (PM10) collected in the Valencian Region (Spain). In the post-target analysis 34 metabolites were identified, of which 11 (3-ketocarburan, carbofuran-7-phenol, carbendazim, desmethylisoproturon, ethiofencarb-sulfoxide, malaoxon, methiocarb-sulfoxide, N-(2-ethyl-6-methylphenyl)-L-alanine, omethoate, 2-hydroxy-terbuthylazine, and THPAM) were confirmed using analytical standards. The semiquantitative estimated concentration ranged between 6.78 and 198.31 pg m−3. Likewise, two unknown degradation products of malaoxon and fenhexamid were elucidated in the non-target screening.

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