Determination of Residues of 3 Triazole Bactericides in Edible Fungi by High Performance Liquid Chromatography Based on Evaporation-Assisted Dispersive Liquid-Liquid Microextraction with Suspension Solidification

A method for the determination of residues of 3 triazole bactericides, including myclobutanil, bitertanol and propiconazole, in edible fungi by high performance liquid chromatography based on evaporation-assisted dispersive liquid-liquid microextraction with suspension solidification was proposed. The edible fungus sample (1.0 g) was chopped and put into a 10 mL-centrifuge tube, and 2 mL of acetonitrile was added for extraction by centrifugation. The supernatant (1 mL) and 4 mL of water were added into a 10 mL-centrifuge tube, and 160 μL of undecanoic acid (as extraction agent, with density lower than that of water), 150 μL of trichloromethane (as volatile solvent, with density higher than that of water) and 0.30 g of sodium chloride were added successively. Then the mixed solution was heated at 85 ℃ for 8 min, and undecanoic acid was solidified at room temperature and floated on the top of the sample solution. The upper solidified substance was taken out and dissolved in 250 μL of methanol, and the solution obtained was passed through 0.22 μm organic filter membrane. The C₁₈ column was used as stationary phase, and 3 triazole bactericides were separated after elution with the mixed solution composed of acetonitrile and water at volume ratio of 7∶3 and determined by high performance liquid chromatograph with diode array detector. The 6 edible fungi, including Lentinus edodes, Pleurotus eryngii, Auricularia auricula, Tremella fuciformis, Hypsizygus marmoreus and Flammulina velutiper, were used as matrixes to draw working curves. It was shown that the linear ranges of 3 triazole bactericides were 14-1 000 μg·kg^-1, with detection limits in the range of 4.0-5.7 μg·kg^-1. Test for recovery was made on the blank samples by standard addition method, giving results in the range of 72.3%-99.4%, with RSDs (n=6) of the determined values less than 5.5%.