QuEChERS-based method for determination of neonicotinoid insecticides in honey.

MICHLIG, MELINA; MAGNI, FLORENCIA; BELDOMÉNICO, HORACIO; DEMONTE, LUISINA; RAATS, DAIANA; BRASCA, ROMINA; MICHLIG, NICOLÁS; REPETTI, MARÍA ROSA

Foz do Iguazú

Workshop; 7th Latin American Pesticide Residue Workshop; 2019

CEPARC-UFSM

Because of the high versatility of neonicotinoid applications for the systemic protection of crops against pests and the great target specificity towards invertebrates, this kind of insecticides 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 [1]. 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 commercial honey. 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 factorial design was carried out considering seven independent variables. For the soaking step the temperature, pH and time were evaluated and the amount of magnesium suphate, sodioum 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]. The results of the validation were satisfactory, since the method presented recoveries between 70-127%, with RSD lower than 18% for the three spike levels 0.25, 1 and 5 µg kg-1. The limit of quantification (LOQ) ranged from 0.25 to 1 µg kg-1. The method developed was adequate for the determination of neonicotinoids in honey samples.