Trace analysis of flubendiamide in bee pollen using enhanced matrix removal-lipid sorbent clean-up and liquid chromatography-electrospray ionization mass spectrometry

Abstract

In this work, a new method has been proposed with the aim of determining flubendiamide, a recently commercialized insecticide, in bee pollen by using liquid chromatography coupled to electrospray ionization mass spectrometry. For this purpose, a novel sample treatment has been proposed that has proven efficient in terms of recovery (average analyte recoveries were between 90% and 102%) and absence of matrix effect, and one which is effective, fast and selective. This involved a solvent extraction using an acetonitrile and water mixture, and a clean-up stage where, in addition to freezing, an enhanced matrix removal-lipid sorbent was successfully used for the first time with this matrix and analyte. The chromatographic conditions were also optimized, by selecting a C18 based column (Gemini® C18) and acetic acid (1 mM) in water and methanol as mobile phase components, allowing elution of flubendiamide in<4 min, with a total analysis time of 14 min. Validation was carried out, with the result that all the parameters studied complied with existing European legislation. It should be noted that the sensitivity of the method was excellent, with a quantification limit (4 μg/kg) well below the maximum residue level established for this insecticide in bee products (50 μg/kg). Finally, several bee pollen samples were analyzed, and flubendiamide residues were not found in any of the cases.