Determination of 20 Pesticide Residues in Edible Fungi by Liquid Chromatography-Tandem Mass Spectrometry

A method by combining liquid chromatography with tandem mass spectrometry was developed to determine the residues of 20 pesticides in edible fungi. Samples were extracted using acetonitrile containing 0.1% acetic acid cleaned-up with anhydrous magnesium sulfate and primary secondary amine (PSA). Measurement on the residues was conducted on the extracts under the modes of electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM), using external standards. The calibration curves of the pesticides had a linear relationship with a correlation coefficients greater than 0.99 in the range of 0.005 to 0.10 mg·kg^-1. The optimized testing conditions included a lower limits of quantitation (LOQs, S/N>10) at 0.005 mg·kg^-1. A test for recovery was performed by adding 0.05 mg·kg^-1 standard pesticides to the mushrooms and white fungi. It was found that the recovery rates ranged from 65.1% to 96.0%, with a relative standard deviations of 2.5%-9.0%. It was concluded that the newly developed methodology was rapid and accurate, and could be applied for the determination of the 20 pesticide residues in edible fungi.