QuEChERS-based method for neonicotinoid insecticides determination in honey from the Argentine livestock-agricultural area

MICHLIG, MELINA P.; BRASCA, ROMINA; DEMONTE, LUISINA D.; MAGNI, FLORENCIA V.; REPETTI, MARÍA R.

Panamá

Workshop; 8th Latin American Pesticide Residue Workshop (LAPRW); 2021

Ministerio de Desarrollo Agropecuario de Panamá (MIDA), Universidad Nacional del Litoral (UNL)

Due to the great versatility of neonicotinoid applications for the systemic protection of crops against pests and the great target specificity towards invertebrates, this kind of insecticide is widely used nowadays. Several studies have shown that neonicotinoids translocate to the nectar and pollen of treated plants, which represents a potential risk to pollinators, and could also end up in honey produced by bees. Thus, a QuEChERS-based methodology was optimized to evaluate the content of neonicotinoid residue in honey samples. Also, the palynological, physicochemical and chromatic properties of 20 % of the samples were measured. In agreement with the requirements of the Argentine legislation, palynological tests showed that each honey sample was unifloral, with a predominance of clover honey[1]. Interestingly, one of them was composed of 50 % soybean pollen (Glycine max L.). The palynological results exhibit the characteristics of the studied area, with low species diversity.Regarding the analytical residue procedure, a two-step experimental design method was carried out to determine the optimal extraction and cleanup conditions for eight neonicotinoids (acetamiprid, clothianidin, dinotefuran, flonicamid, imidacloprid, nitenpyram, thiacloprid and thiamethoxam). Firstly, a two-level fractional design was carried out considering seven independent variables: temperature, pH and time for the sample soaking stage, the concentration of magnesium sulfate and sodium chloride to improve the extraction of the analytes, as well as the amount of C18 and PSA sorbents, were also investigated. After the screening stage, a Box-Behnken design was performed composed of the three significant variables: soaking time and pH, and the amount of PSA. The factorial design methodology combined with the surface response analysis allowed to optimize the process for the efficient extraction of neonicotinoid compounds from honey. The extracts were evaluated on a UHPLC-MS/MS system and quantified with the internal standard method. Afterwards, the proposed method was validated following the SANTE 12682/2019 guidance document, reaching satisfactory results: recoveries between 79-120 % (RSD ≤ 20 %) for the three spiked levels 0.25, 1 and 5 μg kg-1, the LOQs of 0.25 μg kg-1 to acetamiprid and thiacloprid and 1 μg kg-1 for the remaining neonicotinoids. The method was applied to the analysis of 131 honey samples collected from a livestock-agricultural area during the last three honey harvest seasons. Imidacloprid was the most frequently found neonicotinoid, detected in 8 % of the honey samples. Residues of imidacloprid + thiamethoxam were determined in one sample and another sample presented acetamiprid residues. Although neonicotinoid concentrations were low (