Rapid screening of organophosphorus pesticides in honey and bees by liquid chromatography-mass spectrometry

Twenty-two organophosphorus pesticide residues were simultaneously determined in honey and honeybee samples by extraction procedures based on solid-phase and liquid chromatography-atmospheric pressure chemical ionization-mass in positive and negative ionization modes. Pesticides in honeybee samples were extracted by matrix solid phase dispersion with C-18 silica and subsequently eluted with a mixture of dichloromethane-methanol (85:15, v/v). The average recoveries from spiked honeybees (0.5 - 10 mug g(-1)) ranged from 76% for coumaphos to 100% for omethoate, with relative standard deviations between 3 and 17%. Limits of detection were less than or equal to0.13 mug g(-1) and limits of quantification were less than or equal to0.43 mug g(-1). Honey samples required only dilution with water prior to solid phase extraction (SPE) with C-18 silica and further elution with ethyl acetate, methanol and dichloromethane. Mean recoveries from spiked honey (0.1 - 5 mug g(-1)) were between 14% for omethoate to 102% for azinphos ethyl, with relative standard deviations ranging from 2 to 17%. Limits of detection were from 0.01 to 0.24 mug g(-1) and limits of quantification from 0.03 to 0.80 mug g(-1).