Sample preparation methods to analyze fipronil in honey by gas chromatography with electron-capture and mass spectrometric detection

Several sample preparation methods have been assayed to analyze residues of fipronil in honey. After diluting the honey, liquid–liquid extraction (LLE) with organic solvents, and solid-phase extraction (SPE) on commercial cartridges or Florisil-packed column have been tested at three concentration levels: 0.01, 0.1 and 1 mg/kg. LLE with n-hexane or SPE on a Florisil column resulted to be the most suitable procedures to analyze fipronil at trace concentrations. Fipronil was quantified by gas chromatography (GC) with electron-capture detection (ECD) or mass spectrometric (MS) detection after conventional or matrix-matched calibration. The detection limit of fipronil in honey samples was below 1 μg/kg. The degradation of fipronil in honey has also been studied, being identified three minor degradation products in the extracts.