HPLC Determination of Residual Amounts of 3 Pyrethroids in Edible Fungi with Ionic Liquid Dispersive Liquid Liquid Microextraction Based on Solidification of Aqueous Phase

The pulverized and homogenized edible fungi sample was extracted with acetonitrile by vortex agitation. The extract was mixed with the ionic liquid ［HMIM］PF₆, and then injected into 5 mL of water. After adding 50 mg of NaCl, the dispersive liquid liquid microextraction was completed. After centrifugation, the ionic liquid settled onto the bottom of the centrifuge tube. Most of the water in the aqueous phase was removed, and then centrifuge tube was put into freezer (-20 ℃). After the upper aqueous phase was solidified, the ionic liquid at the bottom was taken completely, and diluted by methanol. HPLC was applied to the determination of residual amounts of 3 pyrethroids in the diluent. Eclipse Plus C₁₈ chromatographic column was used as separation column, and 95% (φ) acetonitrile solution was used as mobile phase. Detection at 230 nm was adopted in the determination. Linear relationships between values of peak area and mass fraction of 3 pyrethroids were kept in the same range of 50-5 000 μg·kg^-1, with detection limits (3S/N) in the range of 1.0-1.4 μg·kg^-1 and lower limits of determination (10S/N) in the range of 3.2-4.7 μg·kg^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 71.6%-92.7%, with RSDs (n=5) of determined values in the range of 0.050%-6.6%.