The uptake of a large variety of contaminants of emerging concern (CECs) by crops has already been reported, and the occurrence of phase II metabolites or conjugates has only been detected in plant cell cultures. However, the extent of their formation under cropping conditions is largely unknown. In this study, an analytical strategy to assess the conjugation of 11 CECs in lettuce (Lactuca sativa L.) irrigated with different concentrations (0, 0.05, 0.5, 5, and 50 μg L−1) of CECs was developed. The methodology involved enzymatic digestion with β-glucosidase to obtain the total fraction (free form + conjugates) of CECs. The conjugation fraction was then obtained based on the difference. The highest extent of conjugation (i.e., 27 to 83%) was found with the most hydrophobic compounds, such as bisphenol A, carbamazepine, methyl paraben, and triclosan. So, the CEC conjugate fraction cannot be neglected in the estimate of human daily intake.
Contaminants of emerging concern Uptake Phase II metabolization β-Glycosylate conjugates
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C.H. received a pre-doctoral fellowship (BES-2012-055067) from MINECO. Dr. J. Casas and Dr. C. Flores are acknowledged for their technical assistance with HRMS techniques. Technical assistance in the greenhouse facility given by Mr. M. Massip is kindly acknowledged.
This study was funded by the former Spanish Ministry of Economy and Competitiveness (MINECO) (AGL2014–59353-R and AGL2017–89518-R).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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