Abstract: To achieve simultaneous determination of multiple imidazolinone pesticides in animal-derived foods, the method mentioned by the title was proposed. The 5.00 g of sample (eggs, chicken meat, chicken liver, intestines, tilapia, beef or milk) was taken, and 10 mL of acetonitrile solution containing 1% (volume fraction, the same below) acetic acid was added (for meat samples such as chicken meat, beef and tilapia, additional steps were required including homogenizing 20-30 s, taking 10 mL of acetonitrile solution contaning 1% acetic acid to wash the residue and combining the washing solution with the sample extract). The mixture was vortexed for 20 s, then a QuEChERS extraction salt packet containing 4.0 g of magnesium sulfate anhydrous, 1.0 g of sodium chloride, 1.0 g of sodium citrate dihydrate and 0.5 g of trisodium citrate sesquihydrate was added. After immediate vigorous mixing, the mixture was shaken for 10 min and centrifuged for 5 min. The chicken meat, beef and tilapia samples needed to be frozen at −18 ℃ for 2 h, while the other samples could be processed directly without freezing. The 2 mL of the upper acidic acetonitrile phase was taken and passed through a phospholipid removal PPR solid phase extraction column. The eluate was collected, mixed well, and passed through a 0.22 μm organic filter membrane. The resulting filtrate was analyzed by high performance liquid chromatography-tandem mass spectrometry. The 5 imidazolinone pesticides (imazamox, imazapic, imazapyr, imazaquin and imazethapyr) were separated on Accucore aQ column using a mixture consisting of methanol and 5 mmol · L⁻¹ ammonium formate solution containing 0.1% (volume fraction) formic acid at different volume ratios as the mobile phase for gradient elution. Detection was performed using heated electrospray ionization in positive ion mode with multiple reaction monitoring (MRM) mode. Quantitation was conducted using the standard calibration method (for egg and intestine matrices) combined with the matrix-matched working calibration method (for chicken meat, chicken liver, tilapia, beef and milk matrices). As shown by the results, linear relationships between the corresponding peak areas and mass concentrations of 5 imidazolinone pesticides were in the range of 1-100 μg · L⁻¹, with detection limits (3S/N) in the range of 0.045-0.332 µg · kg⁻¹. Tests for recovery were made on the above 7 blank matrices by the standard addition method, giving results in the range of 67.8%-120%, with RSDs (n=6) of the determined values ranging from 1.0% to 10%. The method was applied to analysis of multiple batches of imported beef and fish, and 5 imidazolinone pesticides were not detected.