Determination of amperozide residues in swine liver using liquid chromatography–mass spectrometry
Amperozide (4-[4,4-bis(4-fluorophenyl)butyl]-N-ethylpiperazine-1-carboxamide) is used in veterinary medicine because of its sedative effect on pigs. A method developed for the detection of amperozide residues in porcine liver using liquid chromatography with thermospray mass spectrometry (LC–MS) is described and compared with LC with electrochemical detection (LC–ED). For LC–ED analysis, the samples were extracted with acetonitrile and cleaned up on a Sep-Pak C18 cartridge. The residues of amperozide were separated on a C8 polymer-based reversed-phase column and determined by using amperometric detection at +1050 mV. For LC–MS analysis, the samples were extracted with ethanol and cleaned using liquid–liquid extraction. After separation on a C8 polymer-based reversed-phase column, the residues were detected by discharge-assisted ionization with positive ion detection MS using single-ion monitoring. The positive discharge ionization produced typical [M + H]+ molecular ions of amperozide (m/z 403) and the internal standard (m/z 431). The limit of quantification for both methods, determined by using spiked blank liver in the concentration range 20–100 µg kg–1, was found to be below 70 µg kg–1.