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.
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