Abstract: A gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (GC-APCI-MS/MS) method was established for the determination of the residues of eight amide herbicides (alachlor, acetochlor, propichlor, butachlor, dichlorochlor, pyrazolam, dimethochlor and metolachlor) in animal-derived foods. The sample pretreatment process involved acetonitrile extraction and enhanced matrix removal (EMR)-lipid cleanup, and ethyl acetate was used to dilute the purified acetonitrile extract instead of solvent conversion. The detection was performed with APCI in the positive ion mode using multi-reaction monitoring (MRM). The results showed that the average recoveries of the eight amide herbicides in spiked pork, pig liver, egg and milk matrices were 63.3%–108%, with relative standard deviation (RSD) 2.51%–13.8%. The limit of detection (LOD) was 0.029–1.3 µg/kg, the limit of quantitation (LOQ) was 0.095–4.2 µg/kg, and the matrix effect was −11%–12%. This method can effectively reduce the matrix effect, and is simple, efficient, accurate, sensitive, and suitable for the rapid quantitative determination of the eight amide herbicides in animal-derived foods.

Key words: atmospheric pressure chemical ionization; gas chromatography-tandem mass spectrometry; amide herbicides; animal-derived food