Residues of pesticide co‐formulants in lettuce and parsley: Identification of decline processes using field trials in different cropping systems

Abstract

BACKGROUND Although co‐formulants constitute a substantial portion of the total plant protection product (PPP) mass applied to crops, data on residue formation and the behaviour of these substances on plants are scarce. In an earlier study we demonstrated that co‐formulants commonly used in PPPs can form considerable residues, i.e., in the low to medium mg/kg range, but normally decline rapidly within few days. In the field trial reported here, we aimed to identify the major decline processes of co‐formulants. Residues of co‐formulants were therefore monitored in parsley and lettuce grown in an open field as well as under foil tunnels equipped with either an overhead or a drip irrigation system. RESULTS Dissipation of three anionic surfactants was markedly faster when crops (parsley and lettuce) were exposed to natural rainfall or irrigation from above compared to drip irrigation. In contrast, the decline of three volatile organic solvents was not affected by rain or irrigation, but was dependent on the crop, with much shorter half‐lives in lettuce than in parsley. Furthermore, dilution through plant growth contributed significantly to the reduction of residues over time. CONCLUSION In this work we substantiate earlier findings on the magnitude and dissipation of residues of anionic surfactants and solvents representing the most important co‐formulant classes. The chosen experimental setup allowed differentiation between decline processes and we confirm that foliar wash‐off is a major dissipation process for anionic surfactants. For volatile organic solvents, dissipation appears to depend on the properties not only of the substance but also of the plant (surface). © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Suspect screening of pesticide co-formulants in fruits, vegetables and leaves by liquid and gas chromatography coupled to high resolution mass accuracy spectrometry: Potential impact on human health

“…Concentrations for linear alkylbenzene sulfonates in the day 0 were 2.3-4.5 mg/kg, which was similar than the mean obtained in leaves (1.35 mg/kg). Nevertheless, the mean value obtained in vegetables and fruits (0.125 mg/kg) was lower than that reported by Balmer et al Regarding N,Ndimethyldecanamide, it was reported an initial quantity of 3.8 and 20 mg/kg in parsley and lettuce (Balmer et al, 2023), but this co-formulant was only detected in leaves in a low quantity in tomato leaf 1 and 2 (0.036 and 0.01 mg/kg).…”

“…There is a recent study that evaluated co-formulants from PPPs monitored in parsley and lettuce crops (Balmer et al, 2023). These PPPs are mainly composed by co-formulants (N,N-dimethyldecanamide, octyl-pirrolidin-2-one, sodium dodecyl sulfate, docusate, linear alkylbenzene sulfonates).…”

“…reported the quantification of 1-and 2-methylnaphthalene in parsley and lettuce, which were analysed by GC-MS/MS (Balmer et al, 2023). The content of these co-formulants were 0.043-0.12 mg/kg in parsley, whereas in lettuce the concentration was lower than the LOQ.…”

“…Another study selected four co-formulants (di-2-ethylhexyl sulfosuccinate, sodium dodecyl sulfate, dimethyl naphthalene sulfonate sodium salt and N,N-dimethyldecanamide), and evaluated their degradation in vegetables and apples under field conditions by LC-tandem mass spectrometry (LC-MS/MS) system (Balmer et al, 2020). In addition, a recent study investigated co-formulant residues from anionic surfactants and solvents in parsley and oak leaf lettuce in three different cropping systems (Balmer et al, 2023). Nevertheless, there are not studies focused on the identification of the possible co-formulants by non-targeted analysis in fruits and vegetables after harvest.…”