Development of precise micro analytical tool to identify potential insecticide hazards to bees in guttation fluid using LC–ESI–MS/MS

Abstract

This paper illustrates the development of a miniaturized and precise analytical tool for biomonitoring of honey bee exposure to insecticides. This is the first work describing an analytical method for determination of very low concentrations of a wide range of insecticides in maize guttation fluid. Seed treatment with systemic insecticides or their foliar application causes the accumulation of compounds in the guttation liquid, which consists of excess water and compounds removed by plants and is a source of water for bees. A micro-QuEChERS protocol using 1 g of sample was used for analysis of over 140 insecticides belonging to 30 different chemical classes by LC–ESI–MS/MS. The determination of insecticides in guttation fluid is a difficult analytical task due to 1) the complexity of the sample matrix, 2) small amounts of test samples and 3) trace levels of analytes (often equal sublethal dose of insecticide for bees). An efficient sample treatment is proposed, involving 1 g of sample, extraction with 1% formic acid in acetonitrile, frozen, ultrasound-assisted, centrifugation and dispersive solid phase extraction with nano graphene oxide. Other tested sorbents: Fe3O4MNPs and two mixtures PSA/C18/GCB and Z-Sep did not give satisfactory parameters during sample purification. The graphene oxide proved to be the best, ensuring negligible matrix effects and analyte recoveries between 70% and 120% with relative standard deviations <20% for most of the compounds studied. The proposed method enables assessment of risk to honey bees resulting from exposure to guttation fluids containing toxic insecticides at very low concentrations.