QuEChERS optimization and validation by experimental design methodology for the determination of neonicotinoid pesticides in honey

DEMONTE, LUISINA; RAATS, DAIANA; MICHLIG, MELINA; MAGNI, FLORENCIA; BELDOMENICO, HORACIO R.; BRASCA, ROMINA; MICHLIG, NICOLÁS; REPETTI, MARÍA R.

Granada

Workshop; 13th European Pesticide Residues Workshop; 2020

Universidad de Granada / Universidad de Almería

Agricultural intensification and pesticide application are found between the main causes of the noticeable decrease of bees in different ecosystems. Neonicotinoids are controversial since studies have suggested that they can translocate to pollen and nectar of treated plants, representing a potential risk to pollinators[1]. However, in Argentina there are at least five compounds from this family registered to be used in a wide variety of crops. Recently, an open-field feeding study was carried out to evaluate the effects on Apis mellifera colonies due to the exposure to imidacloprid, an insecticide belonging to the neonicotinoid family[2]. It was demonstrated that honey samples stored approximately 60% of the loaded imidacloprid. Based on the QuEChERS method developed in such previous study, an optimization of the methodology was performed to evaluate the neonicotinoid residue content in regional honeys. Thus, an experimental design method was carried out to determinate optimal extraction and clean up 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. For the soaking step the temperature, pH and time were evaluated and the amount of magnesium sulphate, sodium chloride, C18 and PSA were also investigated. After the screening stage, a Box-Behnken design composed of the three significant variables: soaking time and pH, and PSA amount, was performed. The extracts were evaluated in a UHPLC MS/MS system and quantified with internal standard method. Afterwards, the proposed method was validated in accordance with SANTE 11813/2017 guidance document[3]. Recoveries were between 79-120%, with RSD lower than 20% for the three spike levels 0.25, 1 and 5 μg kg−1. Limits of quantification (LOQ) ranged from 0.25 to 1 µg kg-1. The developed method was applied for analysing honeys from apiaries located in diverse agroecosystems.