A miniaturized QuEChERS extraction method followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed to analyze thiamethoxam and imidacloprid in 0.3 g of lyophilized Africanized honey bees (Apis mellifera L.). The work aimed to estimate honey bees' exposure to pesticides at the nanogram/gram (ng g-1) levels, using small sample and reagent quantities. Low amounts of solvents and salts were employed - 15× less than used in traditional methods. Average recoveries ranged from 64.5% to 99.7%, with repeatability below 20% for samples spiked at 3 and 167 ng g-1. LOD and LOQ were 0.7, and 3 ng g-1 for both pesticides. Applying the proposed approach, honey bee samples from different apiaries from the State of São Paulo (Brazil) were analyzed. The pesticides were detected in concentrations between 7.0 and 27.0 ng g-1. Thus, the proposed method can be used as a greener alternative to analyze the two neonicotinoids at trace levels in small quantities of bees, consequently saving chemicals and waste.
Keywords: QuEChERS; honey bees; mass spectrometry; miniaturization; neonicotinoids.