Summary
A method to determine residues of the insecticide rotenone in honey using high-performance liquid chromatography (HPLC) is described. The sample was extracted with an acetone/water mixture, followed by a liquid/liquid partition with diethyl ether. A solid-phase extraction (SPE) clean-up step on alumina neutral cartridge was then performed. The chromatographic analysis was conducted on a C18 column (250 × 4 mm, 5 µm) using acetonitrile-water (65:35, v/v) as mobile phase. Rotenone was detected in the ultraviolet range at a wavelength of 295 nm. The specificity of the method was demonstrated through analyses of raw and commercial honey samples. The limit of detection was equal to 40 µg kg^–1. The precision and accuracy of the method were evaluated trueness honey samples spiked at three concentration levels (100-250-500 µg kg^–1). The intra-laboratory coefficient of variation (from 9.2 to 10.6%) and mean recovery values (from 81.4 to 86.6%) were satisfactory. The calibration curve was linear in the range 0.125-2 µg ml^–1, with a determination coefficient R2 of 0.9999. Rotenone levels in honey samples from bees treated with this miticide were in the range 120-430 µg kg^–1.

Keywords
High-performance liquid chromatography, Honey, Rotenone, Solid-phase extraction.