Determination of chlordimeform and its metabolite residue in milk by gas chromatography–tandem mass spectrometry

Herein, the determination of chlordimeform and its metabolite 4-chloro-2-methylaniline residue in milk was performed for the first time using gas chromatography–tandem mass spectrometry (GC–MS/MS). Samples were extracted using acetonitrile, and cleaned using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. Separation was performed using the DB-17 MS column. It was detected in a selected reaction monitoring (SRM) mode and quantified using a matrix-matched isotope internal standard method. Under optimal conditions, a good linear relationship was observed in the concentration range of 10–200 µg/kg. The limit of quantitation was 10.0 µg/kg. The spiked recoveries for the target substance ranged from 84.5 % to 107.3 %, with relative standard deviations (RSD) of <7.2 %. The spiked samples were further confirmed by gas chromatography–quadrupole-Orbitrap high-resolution mass spectrometry (GC–Orbitrap HRMS). The combined method resulted in high accuracy and sensitivity and was suitable for the determination of chlordimeform and its metabolite 4-chloro-2-methylaniline residue in milk.