Validation of a Rapid Multiresidue Method for the Determination of Pesticide Residues in Vine Leaves. Comparison of the Results According to the Different Conservation Methods

Abstract

The QuEChERS method was applied to the determination of pesticide residues in vine (Vitis vinifera) leaves by LC-MSMS. The method was validated in-house for 33 pesticides representing 17 different chemical groups, that are most commonly used in grape production. Recoveries for the pesticides tested ranged from 75 to 104%, and repeatability and reproducibility relative standard deviations (RSDr% and RSDRw%) were less than 20%. The method was applied to the analysis of pesticide residues in 17 market brands of vine leaves processed according to three different preservation methods and sampled from the Lebanese market. Dried vine leaves were more contaminated with pesticide residues than those preserved in brine or stuffed vine leaves. The systemic fungicides were the most frequently detected among all the phytosanitary compounds usually applied to grape production. Brine-preserved and stuffed vine leaves contained lower concentrations of the residues but still contained a cocktail of different pesticides.

The Effects of Formulation on Imidacloprid Dissipation in Grapes and Vine Leaves and on Required Pre-Harvest Intervals under Lebanese Climatic Conditions

“…Method validation was implemented according to Hayar et al [ 7 ]. The following parameters, as required by EU SANTE/12682/2019 [ 42 ], were established: linearity (R 2 ), recovery (RM%), within-laboratory repeatability (RSD r %) and reproducibility (RSD RW %) and the limit of detection and quantification (LOD and LOQ, respectively).…”

“…As per Hayar et al [ 7 ], linearity was performed by first preparing a stock solution of 1000 mg kg −1 of imidacloprid standard in acetonitrile. Afterwards, aliquot solutions were obtained by serial dilution with 6 concentrations ranging from 5 to 500 µg kg −1 .…”

“…Yet such a goal may be impossible to attain for some crops due to lack of specific MRLs. This the case for vine leaves, for which no specified legal limits for pesticide residue levels have been set by national and international organizations; as a consequence, an MRL that corresponds to the limit of detection (LOD) of the analytical method for the molecules applied on grapevines is assigned for this commodity, i.e., at the European Union level [ 5 , 6 , 7 , 8 , 9 ].…”

Occurrence of Fungicides in Vineyard and the Surrounding Environment

“…As shown in Figure 4, both protocols can be applied for the analysis of the target fungicides, except for metalaxyl whose signal is reduced by drying the leaves. Nevertheless, it appears to be an interesting approach since the drying of the leaves is a common step to preserve the samples avoiding their deterioration [14]. In addition, some commercial products based on leaves, such as tea, are sold in dry format (small pieces or powder).…”

“…QuEChERS (a quick, easy, cheap, effective, rugged and safe method) is the preferred extraction technique for the determination of fungicides in vine leaves [14,15]. Besides, for other leaf samples, such as tea, other methodologies have also been employed for the extraction of pesticides, including solid-phase microextraction (SPME), solid-phase extraction (SPE), matrix solid-phase dispersion (MSPD), dispersive solid-phase extraction (d-SPE), pressurized liquid extraction (PLE) and liquid-liquid extraction (LLE) [16][17][18][19].…”