Abstract: A solid-phase extraction and ultrahigh performance liquid chromatography-tandem mass spectrometry method has been developed for the determination of DNOC residue in animal-origin foods. Samples were extracted with acetone-hexane (1:2, V/V) after high-speed homogenization. The crude extract was purified on Oasis HLB solid phase extraction column to remove fat and inorganic salts, which could effectively reduce the background interference generated by complex matrix in samples. The DNOC residue was separated on BEH C18 (50 mm × 2.1 mm, 1.7μm) column using acetonitrile-water as the mobile phase by gradient elution and detected using a tandem mass analyzer in the multi-reaction monitoring (MRM) mode. The developed method exhibited an excellent linear relationship (r＞0.999) and a detection limit of 0.005 mg/kg. At the spiked levels of 0.005, 0.01 mg/kg and 0.02 mg/kg, the average recovery rates for DNOC were in the range of 82.6%－108% with a relative standard deviation (RSD) of less than 10% (n = 6). This method proved rapid, accurate and highly sensitive and can therefore be used for the determination of DNOC residue in animal-origin foods.

Key words: solid-phase extraction (SPE), ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), DNOC, animal-origin food, herbicide